bp (set breakpoint)

Description of the 'bp' command in HyperDbg.

Command

bp

Syntax

bp [Address (hex)] [pid ProcessId (hex)] [tid ThreadId (hex)] [core CoreId (hex)]

Description

Puts a breakpoint (0xcc) on the target function in user-mode and kernel-mode.

In HyperDbg, the 'bp' breakpoints are NOT events. If you want to use breakpoint in an event-like form (e.g., if you want to create logs using script-engine), you should use !epthook command instead.

If you use the 'bp' command, HyperDbg won't hide your breakpoint for the applications that read the memory. The only reason to use 'bp' instead of !epthook is that 'bp' is guaranteed to keep debuggee in a halt state (in Debugger Mode); thus, nothing will change during its execution. However, the in !epthook the guest will be continued for some time, and you lose the current context.

Parameters

[Address (hex)]

The Virtual address of where we want to put a breakpoint.

[pid ProcessId (hex)] [tid ThreadId (hex)] [core CoreId (hex)] (optional)

Optional value to trigger breakpoint in just one special process or one special thread, or one special core. Add pid xx to your command or tid yy or core zz; thus, the command will be executed if the process id is equal to xx or the thread id is equal to yy or the core is equal to zz . If you don't specify these options, then by default, you receive breakpoints on all conditions. See the Remarks section for more information about pid.

Context

As the Context, HyperDbg sends the virtual address of where the breakpoint is triggered (RIP of the triggered breakpoint).

Examples

If you want to put breakpoints on nt!ExAllocatePoolWithTag, nt!ExAllocatePoolWithTag+5,nt!ExAllocatePoolWithTag+@rax+5, fffff801639b1035, fffff801639b103a, and fffff801639b103f, you can use the following commands.

0: kHyperDbg> bp nt!ExAllocatePoolWithTag

0: kHyperDbg> bp nt!ExAllocatePoolWithTag+5

0: kHyperDbg> bp nt!ExAllocatePoolWithTag+@rax+5

0: kHyperDbg> bp fffff801`639b1035

0: kHyperDbg> bp fffff801`639b103a

0: kHyperDbg> bp fffff801`639b103f

After that, you can see a list of active breakpoints using the 'bl' command.

HyperDbg> bl
id   address           status
--   ---------------   --------
01   fffff801639b1030  enabled
02   fffff801639b1035  enabled
03   fffff801639b1040  enabled
04   fffff801639b1035  enabled
05   fffff801639b103a  enabled
06  fffff801639b103f  enabled

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 Address to your target virtual address that you want to put a breakpoint on it, and fill Pid to your special process id, and/or Tid to your special thread id, and/or Core to your special core.

typedef struct _DEBUGGEE_BP_PACKET {

  UINT64 Address;
  UINT32 Pid;
  UINT32 Tid;
  UINT32 Core;
  UINT32 Result;

} DEBUGGEE_BP_PACKET, *PDEBUGGEE_BP_PACKET;

If you want your breakpoint to be triggered for all processes, threads, and cores, then choose DEBUGGEE_BP_APPLY_TO_ALL_PROCESSES, DEBUGGEE_BP_APPLY_TO_ALL_THREADS, DEBUGGEE_BP_APPLY_TO_ALL_CORES.

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_BP 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_BP

In the returned structure, the Result is filled by the kernel.

If the Result is DEBUGEER_OPERATION_WAS_SUCCESSFULL, then the operation was successful. Otherwise, the returned result is an error.

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

BOOLEAN KdSendBpPacketToDebuggee(PDEBUGGEE_BP_PACKET BpPacket);

Remarks

In this command, pid xx does not mean that we will change the layout to a new process, it means that the address should be available in the current process layout but will be triggered only on the process with process id equal to xx, you can use the '.process' command to switch to a new process if you want to put a breakpoint on the layout of another process.

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