bp (set breakpoint)

Description of 'bp' command in HyperDbg.

Command

bp

Syntax

bp [address] [pid (hex value)] [core (hex value)] [imm (yes|no)] [event options]

Description

Puts a hidden breakpoint (0xcc) on the target function in user-mode and kernel-mode without modifying the content of memory in the case of reading/writing.

In HyperDbg, the 'bp' command is the same as the '!epthook' command.

Parameters

[address]

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

[pid (hex value)]

Optional value to trigger the event in just a specific process. Add pid xx to your command; thus, the command will be executed if the process id is equal to xx. If you don't specify this option, then by default, you receive events on all processes.

[core (hex value)]

Optional value to trigger the event in just a specific core. Add core xx to your command thus command will be executed if core id is equal to xx. If you don't specify this option, then by default, you receive events on all cores.

[imm (yes|no)]

Optional value in which yes means the results (printed texts in scripts) should be delivered immediately to the debugger. no means that the results can be accumulated and delivered as a couple of messages when the buffer is full; thus, it's substantially faster but not real-time. By default, this value is set to yes.

[event options]

Regular event parameters are used in HyperDbg events. (For more information, read this topic)

Context

As the Context (r8 in custom code and rdx in condition code register) to the event trigger, HyperDbg sends the virtual address of where put the hidden breakpoint.

Debugger

This event supports three debugging mechanisms.

  • Break

  • Script

  • Custom Code

Please read "How to create a condition?" if you need a conditional event, a conditional event can be used in all "Break", "Script", and "Custom Code".

Break

Imagine we want to put a breakpoint on fffff800`4ed6f010, this will break into the debugger when the target address hits and gives the control back to you.

HyperDbg> bp fffff800`4ed6f010

Script

Using the following command, you can use HyperDbg's Script Engine. You should replace the string between braces (HyperDbg Script Here) with your script. You can find script examples here.

HyperDbg> bp fffff800`4ed6f010 script { HyperDbg Script Here }

The above command when messages don't need to be delivered immediately.

HyperDbg> bp fffff800`4ed6f010 script { HyperDbg Script Here } imm no

Script (From File)

If you saved your script into a file, then you can add file: instead of a script and append the file path to it. For example, the following examples show how you can run a script from file:c:\users\sina\desktop\script.txt.

HyperDbg> bp fffff800`4ed6f010 script {file:c:\users\sina\desktop\script.txt}

You can use event forwarding to forward the event monitoring results from this event and other events to an external source, e.g., File, NamedPipe, or TCP Socket. This way, you can use HyperDbg as a monitoring tool and gather your target system's behavior and use it later or analyze it on other systems.

Custom Code

Please read "How to create an action?" to get an idea about how to run the custom buffer code in HyperDbg.

Your custom code will be executed in vmx-root mode. Take a look at this topic for more information. Running code in vmx-root is considered "unsafe".

Run Custom Code (Unconditional)

Putting a breakpoint on fffff801deadbeef and run 3 nops whenever the breakpoint is triggered. Take a look at Run Custom Code for more information.

HyperDbg> bp fffff801deadbeef code {90 90 90}

Run Custom Code (Conditional)

Putting a breakpoint on fffff801deadbeef and run 3 nops whenever the breakpoint is triggered and also 3 nops condition. Take a look at Run Custom Code and how to create a condition for more information.

HyperDbg> bp fffff801deadbeef code {90 90 90} condition {90 90 90}

Keep in mind; a conditional event can be used in Breaking to Debugger and Running Scripts too.

IOCTL

This command uses the same method to send IOCTL for regular events.

Use HIDDEN_HOOK_EXEC_CC as EventType, and send the address of where you want to hook in OptionalParam1in DEBUGGER_GENERAL_EVENT_DETAIL.

Design

Take a look at "Design of !epthook" to see how does it work.

Remarks

You can disable or clear breakpoints using the 'events' command.

You shouldn't use any of !monitor, !epthook, bp, and !epthook2 commands on the same page (4KB) simultaneously. For example, when you put a hidden hook (!epthook2) on 0x10000005, you shouldn't use any of !monitor or !epthook or bp commands on the address starting from 0x10000000 to 0x10000fff.

You can use !epthook or bp (just !epthook not !epthook2 and not !monitor) on two or more addresses on the same page (means that you can use the !epthook or bp multiple times for addresses between a single page or putting multiple hidden breakpoints on a single page). But you can't use !monitor or !epthook2 twice on the same page.

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

Requirements

Post-Nehalem Processor (EPT)

Processor with Execute-only Pages Support

!epthook (hidden hook with EPT - stealth breakpoints)

!epthook2 (hidden hook with EPT - detours)