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Description of '!u, !u64, !u2 !u32' commands in HyperDbg.

!u, !u64, !u2, !u32 (disassemble physical address)

Command

!u

!u64

!u2

!u32

Syntax

!u [Address (hex)] [l Length (hex)]

!u64 [Address (hex)] [l Length (hex)]

!u2 [Address (hex)] [l Length (hex)]

!u32 [Address (hex)] [l Length (hex)]

{% hint style="info" %} !u and !u64 disassembles as x64 while !u2 and !u32 adisassembles as x86. !u and !u64 are the same commands while !u2 and !u32 are the same. {% endhint %}

Description

Shows the assembly regarding memory content at the physical address hex form.

Parameters

[Address (hex)]

The physical address of where we want to start to disassemble its memory.

[l Length (hex)] (optional)

The length (byte) in hex format.

{% hint style="danger" %} Process ID doesn't make sense in physical memory. If you specify pid, then it is ignored. {% endhint %}

Examples

The following command is used when we want to disassemble the content of memory (x64) at 1000 with length of 0x50bytes.

HyperDbg> !u 1000 l 50
00000000`00001000 0B 00                               or eax, dword ptr ds:[rax]
00000000`00001002 00 00                               add byte ptr ds:[rax], al
00000000`00001004 00 00                               add byte ptr ds:[rax], al
00000000`00001006 00 00                               add byte ptr ds:[rax], al
00000000`00001008 00 00                               add byte ptr ds:[rax], al
00000000`0000100a 86 80 D3 10 02 00                   xchg byte ptr ds:[rax+0x210D3], al
00000000`00001010 00 06                               add byte ptr ds:[rsi], al
00000000`00001012 01 01                               add dword ptr ds:[rcx], eax
00000000`00001014 00 00                               add byte ptr ds:[rax], al
00000000`00001016 00 00                               add byte ptr ds:[rax], al
00000000`00001018 03 01                               add eax, dword ptr ds:[rcx]
00000000`0000101a 00 00                               add byte ptr ds:[rax], al
00000000`0000101c 00 00                               add byte ptr ds:[rax], al
00000000`0000101e 00 00                               add byte ptr ds:[rax], al
00000000`00001020 00 10                               add byte ptr ds:[rax], dl
00000000`00001022 FA                                  cli
00000000`00001023 39 00                               cmp dword ptr ds:[rax], eax
00000000`00001025 F8                                  clc

The following command is used when we want to disassemble the content of memory (x64) at @rax+@rbx with length of 0x50bytes.

Note that the result of @rax+@rbx is 0x1000 in this case.

HyperDbg> !u @rax+@rbx l 50
00000000`00001000 0B 00                               or eax, dword ptr ds:[rax]
00000000`00001002 00 00                               add byte ptr ds:[rax], al
00000000`00001004 00 00                               add byte ptr ds:[rax], al
00000000`00001006 00 00                               add byte ptr ds:[rax], al
00000000`00001008 00 00                               add byte ptr ds:[rax], al
00000000`0000100a 86 80 D3 10 02 00                   xchg byte ptr ds:[rax+0x210D3], al
00000000`00001010 00 06                               add byte ptr ds:[rsi], al
00000000`00001012 01 01                               add dword ptr ds:[rcx], eax
00000000`00001014 00 00                               add byte ptr ds:[rax], al
00000000`00001016 00 00                               add byte ptr ds:[rax], al
00000000`00001018 03 01                               add eax, dword ptr ds:[rcx]
00000000`0000101a 00 00                               add byte ptr ds:[rax], al
00000000`0000101c 00 00                               add byte ptr ds:[rax], al
00000000`0000101e 00 00                               add byte ptr ds:[rax], al
00000000`00001020 00 10                               add byte ptr ds:[rax], dl
00000000`00001022 FA                                  cli
00000000`00001023 39 00                               cmp dword ptr ds:[rax], eax
00000000`00001025 F8                                  clc

The following example shows the assembly content of memory (x64) at 1000.

HyperDbg> !u 1000
00000000`00001000 0B 00                               or eax, dword ptr ds:[rax]
00000000`00001002 00 00                               add byte ptr ds:[rax], al
00000000`00001004 00 00                               add byte ptr ds:[rax], al
00000000`00001006 00 00                               add byte ptr ds:[rax], al
00000000`00001008 00 00                               add byte ptr ds:[rax], al
00000000`0000100a 86 80 D3 10 02 00                   xchg byte ptr ds:[rax+0x210D3], al
00000000`00001010 00 06                               add byte ptr ds:[rsi], al
00000000`00001012 01 01                               add dword ptr ds:[rcx], eax
00000000`00001014 00 00                               add byte ptr ds:[rax], al
00000000`00001016 00 00                               add byte ptr ds:[rax], al
00000000`00001018 03 01                               add eax, dword ptr ds:[rcx]
00000000`0000101a 00 00                               add byte ptr ds:[rax], al
00000000`0000101c 00 00                               add byte ptr ds:[rax], al
00000000`0000101e 00 00                               add byte ptr ds:[rax], al
00000000`00001020 00 10                               add byte ptr ds:[rax], dl
00000000`00001022 FA                                  cli
00000000`00001023 39 00                               cmp dword ptr ds:[rax], eax
00000000`00001025 F8                                  clc

IOCTL

This function works by calling DeviceIoControl with IOCTL = IOCTL_DEBUGGER_READ_MEMORY , you have to send it in the following structure.

typedef struct _DEBUGGER_READ_MEMORY {

    UINT32 Pid; // Read from cr3 of what process
    UINT64 Address;
    UINT32 Size;
    DEBUGGER_READ_MEMORY_TYPE MemoryType;
    DEBUGGER_READ_READING_TYPE ReadingType;

} DEBUGGER_READ_MEMORY, * PDEBUGGER_READ_MEMORY;

Where Pid is the process id, Address is the target location address and size is the length of the byte that you need to read.

MemoryTypeis either virtual or physical.

typedef enum _DEBUGGER_READ_MEMORY_TYPE { DEBUGGER_READ_PHYSICAL_ADDRESS, DEBUGGER_READ_VIRTUAL_ADDRESS } DEBUGGER_READ_MEMORY_TYPE;

ReadingType is either from the kernel or from the vmx-root. Currently, only the reading from the kernel is implemented.

typedef enum _DEBUGGER_READ_READING_TYPE { READ_FROM_KERNEL, READ_FROM_VMX_ROOT } DEBUGGER_READ_READING_TYPE;

If you don't want to read from the kernel directly, use the following HyperDbg routine.

void HyperDbgReadMemoryAndDisassemble(DEBUGGER_SHOW_MEMORY_STYLE Style, UINT64 Address,
                        DEBUGGER_READ_MEMORY_TYPE MemoryType,
                        DEBUGGER_READ_READING_TYPE ReadingType, UINT32 Pid,
                        UINT Size);

The above function fills the IOCTL structure and shows the memory content. It is also able to disassemble the memory. You can specify one of the following styles to show the memory.

typedef enum _DEBUGGER_SHOW_MEMORY_STYLE { DEBUGGER_SHOW_COMMAND_DISASSEMBLE64, DEBUGGER_SHOW_COMMAND_DISASSEMBLE32, DEBUGGER_SHOW_COMMAND_DB, DEBUGGER_SHOW_COMMAND_DC, DEBUGGER_SHOW_COMMAND_DQ, DEBUGGER_SHOW_COMMAND_DD } DEBUGGER_SHOW_MEMORY_STYLE;

For disassembling, use the DEBUGGER_SHOW_COMMAND_DISASSEMBLE64 as the Style for x64 disassembling, and for disassembling x86, use the DEBUGGER_SHOW_COMMAND_DISASSEMBLE32.

In the debugger mode, HyperDbg uses the exact same structure, you should send the above structure over serial to the debuggee which is paused in vmx-root mode.

You should send the above structure with DEBUGGER_REMOTE_PACKET_REQUESTED_ACTION_ON_VMX_ROOT_READ_MEMORY as RequestedAction and DEBUGGER_REMOTE_PACKET_TYPE_DEBUGGER_TO_DEBUGGEE_EXECUTE_ON_VMX_ROOT as PacketType.

In return, the debuggee sends the above structure with the following type.

DEBUGGER_REMOTE_PACKET_REQUESTED_ACTION_DEBUGGEE_RESULT_OF_READING_MEMORY

The following function is responsible for sending reading memory in the debugger.

BOOLEAN KdSendReadMemoryPacketToDebuggee(PDEBUGGER_READ_MEMORY ReadMem);

Remarks

  • If you don't specify the length, the default length for HyperDbg is 0x40 Bytes.

HyperDbg won't remove breakpoints previously set using the 'bp' command if you're disassembling or reading the memory of a special physical address. However, for the virtual addresses, HyperDbg ignores breakpoints and shows the target location's real value.

{% hint style="warning" %} Please note that you should specify space between 'l' and the length in HyperDbg. For example, 'l10' is invalid, but 'l 10' is valid. (It's opposed to windbg). {% endhint %}

{% hint style="success" %} HyperDbg uses Zydis as its core disassembler. {% endhint %}

{% hint style="info" %} Physical addresses are not validated in HyperDbg, which means if you access an invalid physical address, then the debuggee halts or crashes. {% endhint %}

This command is guaranteed to keep debuggee in a halt state (in Debugger Mode); thus, nothing will change during its execution.

Requirements

None

Related

Zydis

u (disassemble virtual address)

a (assemble virtual address)

!a (assemble physical address)