Evtx.BinaryParser.OverrunBufferException raised unexpectedly

[john-corcoran]

Hi,

I'm seeing exception Evtx.BinaryParser.OverrunBufferException raised unexpectedly when parsing event logs "Microsoft-Windows-Windows Firewall With Advanced Security%4Firewall.evtx", "Microsoft-Windows-WindowsUpdateClient%4Operational.evtx", and "Microsoft-Windows-CAPI2%4Operational.evtx" (all extracted from a Windows 7 testing instance) using evtx_dump.py.

For Microsoft-Windows-Windows Firewall With Advanced Security%4Firewall.evtx, the same behaviour is seen across Windows with Python 2.7 and Ubuntu with Python 2.7 / 3.5. Traceback from Ubuntu with Python 3.5 as follows:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 273, in unpack_byte
    return struct.unpack_from("<B", self._buf, o)[0]
struct.error: unpack_from requires a buffer of at least 1 bytes

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/bin/evtx_dump.py", line 42, in <module>
    main()
  File "/home/user/.local/bin/evtx_dump.py", line 37, in main
    print(record.xml())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Evtx.py", line 481, in xml
    return e_views.evtx_record_xml_view(self)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 204, in evtx_record_xml_view
    return render_root_node(record.root())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 182, in render_root_node
    for sub in root_node.substitutions():
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 64, in __call__
    cache[key] = self.func(*args, **kw)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 1001, in substitutions
    ofs = self.tag_and_children_length()
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 962, in tag_and_children_length
    for child in self.children():
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 64, in __call__
    cache[key] = self.func(*args, **kw)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 952, in children
    return self._children(end_tokens=[SYSTEM_TOKENS.EndOfStreamToken])
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 153, in _children
    self._chunk, self)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 777, in __init__
    parent=self)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Evtx.py", line 398, in add_template
    self._load_templates()
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Evtx.py", line 380, in _load_templates
    token = self.unpack_byte(ofs - 10)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 275, in unpack_byte
    raise OverrunBufferException(o, len(self._buf))
Evtx.BinaryParser.OverrunBufferException: Tried to parse beyond the end of the file (read: 0x240f0ff7, buffer length: 0x101000)

For Microsoft-Windows-WindowsUpdateClient%4Operational.evtx, Python 3.5 on Ubuntu gives Evtx.BinaryParser.OverrunBufferException, while Python 2.7 on Windows / Ubuntu gives a MemoryError. Python 3.5 traceback as follows:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 273, in unpack_byte
    return struct.unpack_from("<B", self._buf, o)[0]
struct.error: unpack_from requires a buffer of at least 1 bytes

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/bin/evtx_dump.py", line 42, in <module>
    main()
  File "/home/user/.local/bin/evtx_dump.py", line 37, in main
    print(record.xml())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Evtx.py", line 481, in xml
    return e_views.evtx_record_xml_view(self)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 204, in evtx_record_xml_view
    return render_root_node(record.root())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 182, in render_root_node
    for sub in root_node.substitutions():
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 64, in __call__
    cache[key] = self.func(*args, **kw)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 1006, in substitutions
    type_ = self.unpack_byte(ofs + 0x2)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 275, in unpack_byte
    raise OverrunBufferException(o, len(self._buf))
Evtx.BinaryParser.OverrunBufferException: Tried to parse beyond the end of the file (read: 0x101000, buffer length: 0x101000)

Python 2.7 traceback (from Ubuntu) as follows:

Traceback (most recent call last):
  File "/home/user/.local/bin/evtx_dump.py", line 42, in <module>
    main()
  File "/home/user/.local/bin/evtx_dump.py", line 37, in main
    print(record.xml())
  File "/home/user/.local/lib/python2.7/site-packages/Evtx/Evtx.py", line 481, in xml
    return e_views.evtx_record_xml_view(self)
  File "/home/user/.local/lib/python2.7/site-packages/Evtx/Views.py", line 204, in evtx_record_xml_view
    return render_root_node(record.root())
  File "/home/user/.local/lib/python2.7/site-packages/Evtx/Views.py", line 182, in render_root_node
    for sub in root_node.substitutions():
  File "/home/user/.local/lib/python2.7/site-packages/Evtx/BinaryParser.py", line 64, in __call__
    cache[key] = self.func(*args, **kw)
  File "/home/user/.local/lib/python2.7/site-packages/Evtx/Nodes.py", line 1004, in substitutions
    for _ in range(sub_count):
MemoryError

And similarly for Microsoft-Windows-CAPI2%4Operational.evtx, Python 3.5 on Ubuntu gives Evtx.BinaryParser.OverrunBufferException, while Python 2.7 on Windows / Ubuntu BSODs / has process 'Killed'. Traceback for Python 3.5 on Ubuntu as follows:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 302, in unpack_word
    return struct.unpack_from("<H", self._buf, o)[0]
struct.error: unpack_from requires a buffer of at least 2 bytes

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/bin/evtx_dump.py", line 42, in <module>
    main()
  File "/home/user/.local/bin/evtx_dump.py", line 37, in main
    print(record.xml())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Evtx.py", line 481, in xml
    return e_views.evtx_record_xml_view(self)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 204, in evtx_record_xml_view
    return render_root_node(record.root())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 191, in render_root_node
    return render_root_node_with_subs(root_node, subs)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 176, in render_root_node_with_subs
    rec(c, acc)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 126, in rec
    rec(child, acc)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 126, in rec
    rec(child, acc)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 166, in rec
    sub = render_root_node(sub.root())
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Views.py", line 182, in render_root_node
    for sub in root_node.substitutions():
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 64, in __call__
    cache[key] = self.func(*args, **kw)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/Nodes.py", line 1005, in substitutions
    size = self.unpack_word(ofs)
  File "/home/user/.local/lib/python3.5/site-packages/Evtx/BinaryParser.py", line 304, in unpack_word
    raise OverrunBufferException(o, len(self._buf))
Evtx.BinaryParser.OverrunBufferException: Tried to parse beyond the end of the file (read: 0x101000, buffer length: 0x101000)

I can forward the EVTX files in question if that assists?

[williballenthin]

hey @john-corcoran

Thanks for raising this issue. The easiest way to triage it will be to share the .evtx file. I'd be happy to take a peek if you send to my email: [email protected]

[williballenthin]

file structure looks ok:

λ C:\Users\user\env2\Scripts\python ..\scripts\evtx_info.py data\issue_46.evtx
Information from file header:
Format version  : 3.1
Flags           : 0x00000000
File is         : clean
Log is full     : no
Current chunk   : 3 of 16
Oldest chunk    : 5
Next record#    : 521
Check sum       : pass

Information from chunks:
  Chunk file (first/last)     log (first/last)      Header Data
- ----- --------------------- --------------------- ------ ------
      1        417       441         417       441   pass   pass
      2        442       466         442       466   pass   pass
      3        467       499         467       499   pass   pass
*     4        500       520         500       520   pass   pass
>     5        104       129         104       129   pass   pass
      6        130       150         130       150   pass   pass
      7        151       180         151       180   pass   pass
      8        181       205         181       205   pass   pass
      9        206       226         206       226   pass   pass
     10        227       252         227       252   pass   pass
     11        253       283         253       283   pass   pass
     12        284       304         284       304   pass   pass
     13        305       335         305       335   pass   pass
     14        336       360         336       360   pass   pass
     15        361       387         361       387   pass   pass
     16        388       416         388       416   pass   pass

[williballenthin]

Seems like the very first record in the evtx file is problematic:

magic: 0x2a2a
size: 0x17a0
num: 417
ts: 2017-11-14T11:32:41.189631
substitutions count: 20
substitutions count: 1124080761

Clearly 1124080761 is not a reasonable number of substitutions.

[williballenthin]

there's a root note being parsed at 0x1836, with substitution count being parsed at 0x1844:

19:44:21,0731 [root :1046][INFO    ] root node: 0x1836
19:44:21,0732 [root :1047][INFO    ] ofs: 0xe (abs: 0x1844)
19:44:21,0732 [root :1048][INFO    ] sub count: 1124080761

but this doesn't look quite right:

1830h: 00 05 12 00 00 00 01 5C 11 00 00 3F 08 00 00 00  .......\...?.... 
1840h: 00 00 00 B4 79 1C 00 43 00 72 00 79 00 70 00 74  ...´y..C.r.y.p.t 
1850h: 00 52 00 65 00 74 00 72 00 69 00 65 00 76 00 65  .R.e.t.r.i.e.v.e 
1860h: 00 4F 00 62 00 6A 00 65 00 63 00 74 00 42 00 79  .O.b.j.e.c.t.B.y 
1870h: 00 55 00 72 00 6C 00 57 00 69 00 72 00 65 00 00  .U.r.l.W.i.r.e.. 
1880h: 00 02 41 CB 00 00 00 8B 08 00 00 00 00 00 00 4F  ..AË...‹.......O 

the dword at 0x1844 is 0x43001C79, which is crazy. a better interpretation of these bytes is the byte at 0x1845 (value: 0x1C) is number of wchar in the utf-16le string (number of chars: 0x1C) that begins at 0x1847.

need to trace down where the parsing is faulty that leads to these incorrect fields.

[williballenthin]

file structure:

λ C:\Users\user\env2\Scripts\python ..\scripts\evtx_structure.py data\issue_46.evtx  | head -n 400
File header
  magic: ElfFile
  oldest_chunk: 0x4
  current_chunk_number: 0x3
  next_record_number: 0x209
  header_size: 0x80
  minor_version: 0x1
  major_version: 0x3
  header_chunk_size: 0x1000
  chunk_count: 0x10
  flags: 0x0
  checksum: 0x1d883bed
  verify: True
  dirty: False
  full: False
  Chunk
    offset: 0x1000
    magic: ElfChnk
    file_first_record_number: 0x1a1
    file_last_record_number: 0x1b9
    log_first_record_number: 0x1a1
    log_last_record_number: 0x1b9
    header_size: 0x80
    last_record_offset: 0xdf80
    next_record_offset: 0xfe90
    data_checksum: 0x20c08819
    header_checksum: 0xf0aadf4cL
    verify: True
    templates: 1
    Record
      offset: 0x1200
      magic: 0x2a2a
      size: 0x17a0
      number: 0x1a1
      timestamp: 2017-11-14 11:32:41.189631
      verify: True
      RootNode(offset=0x18)
        StreamStartNode(offset=0x18)
        TemplateInstanceNode(offset=0x1c, resident=True, length=0x571)
          TemplateNode(offset=0x26)
            StreamStartNode(offset=0x3e)
            OpenStartElementNode(offset=0x42) --> Event
              AttributeNode(offset=0x65) --> xmlns
                ValueNode(offset=0x7e)
                  WstringTypeNode(offset=0x80) --> http://schemas.microsoft.com/win/2004/08/events/event
              CloseStartElementNode(offset=0xec)
              OpenStartElementNode(offset=0xed) --> System
                CloseStartElementNode(offset=0x10e)
                OpenStartElementNode(offset=0x10f) --> Provider
                  AttributeNode(offset=0x138) --> Name
                    ValueNode(offset=0x14f)
                      WstringTypeNode(offset=0x151) --> Microsoft-Windows-CAPI2
                  AttributeNode(offset=0x181) --> Guid
                    ValueNode(offset=0x198)
                      WstringTypeNode(offset=0x19a) --> {5bbca4a8-b209-48dc-a8c7-b23d3e5216fb}
                  CloseEmptyElementNode(offset=0x1e8)
                OpenStartElementNode(offset=0x1e9) --> EventID
                  AttributeNode(offset=0x210) --> Qualifiers
                    ConditionalSubstitutionNode(offset=0x233)
                  CloseStartElementNode(offset=0x237)
                  ConditionalSubstitutionNode(offset=0x238)
                  CloseElementNode(offset=0x23c)
                OpenStartElementNode(offset=0x23d) --> Version
                  CloseStartElementNode(offset=0x260)
                  ConditionalSubstitutionNode(offset=0x261)
                  CloseElementNode(offset=0x265)
                OpenStartElementNode(offset=0x266) --> Level
                  CloseStartElementNode(offset=0x285)
                  ConditionalSubstitutionNode(offset=0x286)
                  CloseElementNode(offset=0x28a)
                OpenStartElementNode(offset=0x28b) --> Task
                  CloseStartElementNode(offset=0x2a8)
                  ConditionalSubstitutionNode(offset=0x2a9)
                  CloseElementNode(offset=0x2ad)
                OpenStartElementNode(offset=0x2ae) --> Opcode
                  CloseStartElementNode(offset=0x2cf)
                  ConditionalSubstitutionNode(offset=0x2d0)
                  CloseElementNode(offset=0x2d4)
                OpenStartElementNode(offset=0x2d5) --> Keywords
                  CloseStartElementNode(offset=0x2fa)
                  ConditionalSubstitutionNode(offset=0x2fb)
                  CloseElementNode(offset=0x2ff)
                OpenStartElementNode(offset=0x300) --> TimeCreated
                  AttributeNode(offset=0x32f) --> SystemTime
                    ConditionalSubstitutionNode(offset=0x352)
                  CloseEmptyElementNode(offset=0x356)
                OpenStartElementNode(offset=0x357) --> EventRecordID
                  CloseStartElementNode(offset=0x386)
                  ConditionalSubstitutionNode(offset=0x387)
                  CloseElementNode(offset=0x38b)
                OpenStartElementNode(offset=0x38c) --> Correlation
                  AttributeNode(offset=0x3bb) --> ActivityID
                    ConditionalSubstitutionNode(offset=0x3de)
                  AttributeNode(offset=0x3e2) --> RelatedActivityID
                    ConditionalSubstitutionNode(offset=0x413)
                  CloseEmptyElementNode(offset=0x417)
                OpenStartElementNode(offset=0x418) --> Execution
                  AttributeNode(offset=0x443) --> ProcessID
                    ConditionalSubstitutionNode(offset=0x464)
                  AttributeNode(offset=0x468) --> ThreadID
                    ConditionalSubstitutionNode(offset=0x487)
                  CloseEmptyElementNode(offset=0x48b)
                OpenStartElementNode(offset=0x48c) --> Channel
                  CloseStartElementNode(offset=0x4af)
                  ValueNode(offset=0x4b0)
                    WstringTypeNode(offset=0x4b2) --> Microsoft-Windows-CAPI2/Operational
                  CloseElementNode(offset=0x4fa)
                OpenStartElementNode(offset=0x4fb) --> Computer
                  CloseStartElementNode(offset=0x520)
                  ValueNode(offset=0x521)
                    WstringTypeNode(offset=0x523) --> exploited
                  CloseElementNode(offset=0x537)
                OpenStartElementNode(offset=0x538) --> Security
                  AttributeNode(offset=0x561) --> UserID
                    ConditionalSubstitutionNode(offset=0x57c)
                  CloseEmptyElementNode(offset=0x580)
                CloseElementNode(offset=0x581)
              OpenStartElementNode(offset=0x582) --> UserData
                CloseStartElementNode(offset=0x5a7)
                ConditionalSubstitutionNode(offset=0x5a8)
                CloseElementNode(offset=0x5ac)
              CloseElementNode(offset=0x5ad)
            EndOfStreamNode(offset=0x5ae)
      Substitutions(offset=0x5af)
        UnsignedByteTypeNode(offset=0x603) --> 2
        UnsignedByteTypeNode(offset=0x604) --> 2
        UnsignedWordTypeNode(offset=0x605) --> 53
        UnsignedWordTypeNode(offset=0x607) --> 53
        NullTypeNode(offset=0x609)
        Hex64TypeNode(offset=0x609) --> 0x4000000000000036
        FiletimeTypeNode(offset=0x611) --> 2017-11-14 11:32:41.189631
        NullTypeNode(offset=0x619)
        UnsignedDwordTypeNode(offset=0x619) --> 2856
        UnsignedDwordTypeNode(offset=0x61d) --> 608
        UnsignedQwordTypeNode(offset=0x621) --> 417
        UnsignedByteTypeNode(offset=0x629) --> 0
        SIDTypeNode(offset=0x62a) --> S-1-5-18
        NullTypeNode(offset=0x636)
        NullTypeNode(offset=0x636)
        NullTypeNode(offset=0x636)
        NullTypeNode(offset=0x636)
        NullTypeNode(offset=0x636)
        NullTypeNode(offset=0x636)
        BXmlTypeNode(offset=0x636) -->
          RootNode(offset=0x636)
ERROR: 0
    Record
      offset: 0x29a0
      magic: 0x2a2a
      size: 0x790
      number: 0x1a2
      timestamp: 2017-11-14 11:32:41.189631
      verify: True
      RootNode(offset=0x18)
        StreamStartNode(offset=0x18)
        TemplateInstanceNode(offset=0x1c, resident=False)
      Substitutions(offset=0x26)
        UnsignedByteTypeNode(offset=0x7a) --> 4
        UnsignedByteTypeNode(offset=0x7b) --> 2
        UnsignedWordTypeNode(offset=0x7c) --> 41
        UnsignedWordTypeNode(offset=0x7e) --> 41
        NullTypeNode(offset=0x80)
        Hex64TypeNode(offset=0x80) --> 0x4000000000000005
        FiletimeTypeNode(offset=0x88) --> 2017-11-14 11:32:41.189631
        NullTypeNode(offset=0x90)
        UnsignedDwordTypeNode(offset=0x90) --> 2856
        UnsignedDwordTypeNode(offset=0x94) --> 608
        UnsignedQwordTypeNode(offset=0x98) --> 418
        UnsignedByteTypeNode(offset=0xa0) --> 0
        SIDTypeNode(offset=0xa1) --> S-1-5-18
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        BXmlTypeNode(offset=0xad) -->
          RootNode(offset=0xad)
ERROR: Tried to parse beyond the end of the file (read: 0x160c1006, buffer length: 0x101000)
    Record
      offset: 0x3130
      magic: 0x2a2a
      size: 0x1738
      number: 0x1a3
      timestamp: 2017-11-14 11:32:41.189631
      verify: True
      RootNode(offset=0x18)
        StreamStartNode(offset=0x18)
        TemplateInstanceNode(offset=0x1c, resident=False)
      Substitutions(offset=0x26)
        UnsignedByteTypeNode(offset=0x7a) --> 4
        UnsignedByteTypeNode(offset=0x7b) --> 2
        UnsignedWordTypeNode(offset=0x7c) --> 11
        UnsignedWordTypeNode(offset=0x7e) --> 11
        NullTypeNode(offset=0x80)
        Hex64TypeNode(offset=0x80) --> 0x4000000000000003
        FiletimeTypeNode(offset=0x88) --> 2017-11-14 11:32:41.189631
        NullTypeNode(offset=0x90)
        UnsignedDwordTypeNode(offset=0x90) --> 2856
        UnsignedDwordTypeNode(offset=0x94) --> 608
        UnsignedQwordTypeNode(offset=0x98) --> 419
        UnsignedByteTypeNode(offset=0xa0) --> 0
        SIDTypeNode(offset=0xa1) --> S-1-5-18
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        NullTypeNode(offset=0xad)
        BXmlTypeNode(offset=0xad) -->
          RootNode(offset=0xad)
ERROR: Tried to parse beyond the end of the file (read: 0x5341006, buffer length: 0x101000)

[jvaldezjr1]

I have the same problem, but in this instance, I can't share the EVTX files for confidentiality reasons. I have the same parsing problem. I tried to follow some of your steps above for leads, and I will paste the output below. I'm running python 3.7.1.

python D:\tools\Parse-Evtx\scripts\evtx_info.py "Microsoft-Windows-TerminalServices-LocalSessionManager%4Operational.evtx"
Information from file header:
Format version  : 3.1
Flags           : 0x00000001
File is         : dirty
Log is full     : no
Current chunk   : 8 of 9
Oldest chunk    : 1
Next record#    : 1018
Check sum       : pass
Traceback (most recent call last):
  File "D:\tools\Parse-Evtx\scripts\evtx_info.py", line 114, in <module>
    main()
  File "D:\tools\Parse-Evtx\scripts\evtx_info.py", line 57, in main
    chunk_count = sum([1 for c in fh.chunks() if c.verify()])
  File "D:\tools\Parse-Evtx\scripts\evtx_info.py", line 57, in <listcomp>
    chunk_count = sum([1 for c in fh.chunks() if c.verify()])
  File "C:\Python3\lib\site-packages\Evtx\Evtx.py", line 333, in verify
    return self.check_magic() and \
  File "C:\Python3\lib\site-packages\Evtx\Evtx.py", line 308, in check_magic
    return self.magic() == "ElfChnk\x00"
  File "C:\Python3\lib\site-packages\Evtx\BinaryParser.py", line 211, in explicit_length_handler
    return f(offset, length)
  File "C:\Python3\lib\site-packages\Evtx\BinaryParser.py", line 475, in unpack_string
    return self.unpack_binary(offset, length).decode('ascii')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 4: ordinal not in range(128)

Here is the excerpt from evtx_structure.py where it failed.

Chunk
    offset: 0x91000
    magic:   ☻   ☻
    file_first_record_number: 0x20048
    file_last_record_number: 0x12c65ab
    log_first_record_number: 0x2
    log_last_record_number: 0x0
    header_size: 0x20800
    last_record_offset: 0x3
    next_record_offset: 0x20000
    data_checksum: 0x0
    header_checksum: 0x0
    verify: False
Unexpected token encountered
Unexpected token encountered
Traceback (most recent call last):
  File "C:\Python3\lib\site-packages\Evtx\BinaryParser.py", line 273, in unpack_byte
    return struct.unpack_from("<B", self._buf, o)[0]
struct.error: unpack_from requires a buffer of at least 1 bytes

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:\tools\Parse-Evtx\scripts\evtx_structure.py", line 185, in <module>
    main()
  File "D:\tools\Parse-Evtx\scripts\evtx_structure.py", line 180, in main
    for line in formatter.format_header(log.get_file_header()):
  File "D:\tools\Parse-Evtx\scripts\evtx_structure.py", line 66, in format_header
    for line in self.format_chunk(chunk):
  File "D:\tools\Parse-Evtx\scripts\evtx_structure.py", line 89, in format_chunk
    yield self._l("templates: %d" % (len(chunk.templates())))
  File "C:\Python3\lib\site-packages\Evtx\Evtx.py", line 411, in templates
    self._load_templates()
  File "C:\Python3\lib\site-packages\Evtx\Evtx.py", line 380, in _load_templates
    token = self.unpack_byte(ofs - 10)
  File "C:\Python3\lib\site-packages\Evtx\BinaryParser.py", line 275, in unpack_byte
    raise OverrunBufferException(o, len(self._buf))
Evtx.BinaryParser.OverrunBufferException: Tried to parse beyond the end of the file (read: 0x43dbfc, buffer length: 0x101000)

[Cr0n1c]

Experiencing the same exact issues. Any recommendations?

[naggie]

@williballenthin I believe this evt(x) file causes the same exception: https://send.firefox.com/download/1804ced0a1ad523c/#A_E9qDRE3rU1poCUk_zq4g

I hope this helps.

(it's produced by wusa.exe)