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Description of '!db, !dc, !dd, !dq' commands in HyperDbg.

!db, !dc, !dd, !dq (read physical memory)

Command

!db : read memory as Byte values and ASCII characters

!dc : read memory as Double-word values (4 bytes) and ASCII characters

!dd : read memory as Double-word values (4 bytes)

!dq : read memory as Quad-word values (8 bytes)

Syntax

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

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

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

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

Description

Shows the physical address memory content in hex form.

Parameters

[Address (hex)]

The physical address of where we want to read 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 for physical memory, then it is ignored. {% endhint %}

Examples

The following command is used when we want to read the content of memory at 1000 with length of 0x50 in a hex byte format.

HyperDbg> !db 1000 l 50
#       00000000`00001000  0B 00 00 00 00 00 00 00 00 00 86 80 D3 10 02 00  ................
#       00000000`00001010  00 06 01 01 00 00 00 00 03 01 00 00 00 00 00 00  ................
#       00000000`00001020  00 10 FA 39 00 F8 FF FF 00 00 02 00 00 00 00 00  ...9............
#       00000000`00001030  03 01 00 00 00 00 00 00 00 10 FC 39 00 F8 FF FF  ...........9....
#       00000000`00001040  00 00 02 00 00 00 00 00 01 01 00 00 00 00 00 00  ................

The following command is used when we want to read the content of memory after evaluating the expression @rax+@rbx with length of 0x50 in a hex byte format.

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

HyperDbg> !db @rax+@rbx l 50
#       00000000`00001000  0B 00 00 00 00 00 00 00 00 00 86 80 D3 10 02 00  ................
#       00000000`00001010  00 06 01 01 00 00 00 00 03 01 00 00 00 00 00 00  ................
#       00000000`00001020  00 10 FA 39 00 F8 FF FF 00 00 02 00 00 00 00 00  ...9............
#       00000000`00001030  03 01 00 00 00 00 00 00 00 10 FC 39 00 F8 FF FF  ...........9....
#       00000000`00001040  00 00 02 00 00 00 00 00 01 01 00 00 00 00 00 0

The following example shows the content of memory at 1000 in a double-word value (4 bytes) and ASCII characters format.

HyperDbg> !dc 1000
#       00000000`00001000  0000000B 00000000 80860000 000210D3  ................
#       00000000`00001010  01010600 00000000 00000103 00000000  ................
#       00000000`00001020  39FA1000 FFFFF800 00020000 00000000  ...9............
#       00000000`00001030  00000103 00000000 39FC1000 FFFFF800  ...........9....
#       00000000`00001040  00020000 00000000 00000101 00000000  ................
#       00000000`00001050  00005000 00000000 00000020 00000000  .P...... .......
#       00000000`00001060  00000103 00000000 39F8B000 FFFFF800  ...........9....
#       00000000`00001070  00004000 00000000 00000000 00000000  .@..............

The following example shows the content of memory at 1000 in a double-word value (4 bytes) format with the length of 0x10.

0: kHyperDbg> !dd 1000 l 10
#       00000000`00001000  0000000B 00000000 80860000 000210D3

The following example shows the content of memory at 1000 in a quad-word value (8 bytes) format.

0: kHyperDbg> !dq 1000
#       00000000`00001000  00000000`0000000B 000210D3`80860000
#       00000000`00001010  00000000`01010600 00000000`00000103
#       00000000`00001020  FFFFF800`39FA1000 00000000`00020000
#       00000000`00001030  00000000`00000103 FFFFF800`39FC1000
#       00000000`00001040  00000000`00020000 00000000`00000101
#       00000000`00001050  00000000`00005000 00000000`00000020
#       00000000`00001060  00000000`00000103 FFFFF800`39F8B000
#       00000000`00001070  00000000`00004000 00000000`00000000

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_DISASSEMBLE, 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_DISASSEMBLE as the Style.

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 0x80 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 a 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="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

db, dc, dd, dq (read virtual memory)