i (instrumentation step-in)

Description of the 'i' command in HyperDbg.

Command

i

ir

Syntax

i

i [Count (hex)]

ir

ir [Count (hex)]

Description

Executes a single instruction (step-in) and optionally displays the resulting values of all registers and flags. This command only works in the Debugger Mode.

The difference between this command and the 't' command is that no other cores and other threads find a chance to be executed during the stepping process; the system is fully halted, and only the current core will execute just one instruction and halts again.

This command gives you the ability to follow system-calls (SYSCALLs) and all the exceptions (including page-faults) from user-mode to kernel-mode and from kernel-mode to user-mode. For example, in the middle of executing one instruction in user-mode, a page-fault might happen, then if you use this command, the next instruction is in the kernel-mode page-fault handler. Another example, you can follow a syscall from user-mode, then the next instruction is in kernel-mode syscall handler, and this way, you can trace the execution between different rings.

Parameters

[Count (hex)] (optional)

Count of step(s), or how many times perform the stepping operation. If you don't set this argument, then by default, the Count is 1.

Examples

If you want to instrumentation step-in one instruction.

0: kHyperDbg> i
fffff801`68d91267    41 5B                               pop r11

If you want to instrumentation step-in one instruction and view the registers.

0: kHyperDbg> ir
fffff801`68d91269    41 5A                               pop r10
RAX=0000000000000000 RBX=ffff948cbf6599d0 RCX=0000000000000024
RDX=0000000000000000 RSI=0000000000000000 RDI=ffff948cc266d670
RIP=fffff80168d91269 RSP=ffff9305492df6a8 RBP=0000000000000002
R8=0000000000000000  R9=0000000000000000  R10=0000000048564653
R11=0000000000000000 R12=0000000000000000 R13=0000000000000000
R14=ffff948cc266d670 R15=ffff948cc058e6b0 IOPL=00
OF 0  DF 0  IF 0  SF  0
ZF 1  PF 1  CF 0  AXF 0
CS 0010 SS 0018 DS 002b ES 002b FS 0053 GS 002b
RFLAGS=0000000000040046

If you want to instrumentation step-in for 5 instructions.

0: kHyperDbg> i 5
fffff801`68d9126b    9D                                  popfq
fffff801`68d9126c    C3                                  ret
fffff801`63a12948    6A D1                               push 0xFFFFFFFFFFFFFFD1
fffff801`63a1294a    E9 B1 00 00 00                      jmp 0xFFFFF80163A12A00
fffff801`63a12b00    F6 44 24 10 01                      test byte ptr ss:[rsp+0x10], 0x01

IOCTL

This commands works over serial by sending the serial packets to the remote computer.

First of all, you should fill the following structure, set the StepType to the type of step that you want to perform (e.g., step-in, step-over, and instrumentation step-in), and if it's a step-over (only step-over), then if the currently executing instruction is a call instruction, set the IsCurrentInstructionACall to TRUE and also set the length of the current call instruction (if it's a call instruction) to CallLength, so you can hint the debuggee to find the next instruction. In step-over, just set the StepType and set all the other members to null.

typedef struct _DEBUGGEE_STEP_PACKET {

  DEBUGGER_REMOTE_STEPPING_REQUEST StepType;

  //
  // Only in the case of call instructions
  // the 'p' command
  //
  BOOLEAN IsCurrentInstructionACall;
  UINT32 CallLength;

} DEBUGGEE_STEP_PACKET, *PDEBUGGEE_STEP_PACKET;

StepType can be chosen from one of the following types.

typedef enum _DEBUGGER_REMOTE_STEPPING_REQUEST
{
    DEBUGGER_REMOTE_STEPPING_REQUEST_STEP_IN,
    DEBUGGER_REMOTE_STEPPING_REQUEST_INSTRUMENTATION_STEP_IN,
    DEBUGGER_REMOTE_STEPPING_REQUEST_INSTRUMENTATION_STEP_IN_FOR_TRACKING,

    DEBUGGER_REMOTE_STEPPING_REQUEST_STEP_OVER,
    DEBUGGER_REMOTE_STEPPING_REQUEST_STEP_OVER_FOR_GU,
    DEBUGGER_REMOTE_STEPPING_REQUEST_STEP_OVER_FOR_GU_LAST_INSTRUCTION,

} DEBUGGER_REMOTE_STEPPING_REQUEST;

The next step is sending the above structure to the debuggee when debuggee is paused and waiting for new command on vmx-root mode.

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

In return, the debuggee sends a pause packet with the following type.

DEBUGGEE_PAUSING_REASON_DEBUGGEE_STEPPED

The following function is responsible for sending breakpoint buffers in the debugger.

BOOLEAN KdSendStepPacketToDebuggee(DEBUGGER_REMOTE_STEPPING_REQUEST StepRequestType);

Remarks

This command will set a Monitor Trap Flag in debuggee and continue just the current executing core. After executing one instruction, it halts the debuggee again.

If the currently executing instruction is a call instruction, it will follow and enter the call instruction.

HyperDbg guarantees that all cores and threads won't find a chance to be executed between each step in this type of stepping.

If you load symbols and you don't want to see function names, you turn addressconversion off in the 'settings' command.

Requirements

None

Related

p (step-over)

t (step-in)

gu (step-out or go up)