output (create output source for event forwarding)

Description of the 'output' command in HyperDbg.

Command

output

Syntax

output

output [create Name (string)] [file|namedpipe|tcp|module Address (string)]

output [open|close Name (string)]

Description

Create, open, or close a source output for event forwarding.

You can read more about event forwarding here.

Examples of using this mechanism in different programming languages are available here:

GitHub - HyperDbg/event-forwarding-examples: Examples of using "Event Forwarding" mechanism in HyperDbgGitHub

Parameters

[create Name (string)]

The name of the instance output to be created.

[file|namedpipe|tcp|module Address (string)]

Type and address of the target resource.

[open|close Name (string)]

The action of this command or whether this command tries to open an output source or close it combined with its name.

If you don't specify any parameters to the 'output' command, it shows a list of output sources and their status.

Examples

The following command creates an output source, which is a file and the results of the command (script) will be saved into the c:\users\sina\desktop\output.txt.

HyperDbg> output create MyOutputName1 file c:\users\sina\desktop\output.txt

The following command creates an output source, which is a tcp and the results of the command (script) will be sent into the 192.168.1.10:8080.

HyperDbg> output create MyOutputName2 tcp 192.168.1.10:8080

The following command creates an output source, which is a namedpipe and the results of the command (script) will be sent into the \\.\Pipe\HyperDbgOutput.

HyperDbg> output create MyOutputName3 namedpipe \\.\Pipe\HyperDbgOutput

You cannot use the above resources until you open them using the following command. This command opens an output source (named "MyOutputName1") that was previously created by the output's create parameter.

HyperDbg> output open MyOutputName1

When you finished using an output source, you can close it using the following command. Once you close an output source, you cannot use it anymore, and also, you CANNOT open it again, but once again, you can create a new source with the same address but with a different name.

HyperDbg> output close MyOutputName1

After creating and opening the output source, you can use its name in all HyperDbg events. You should pass output {MyOutputName1} when you are creating an event, for example !syscall is an event so that you can use it like this :

HyperDbg> !syscall script { print(@rax); } output {MyOutputName1}

It is also possible to send the results to several output sources. You should separate the output names with , .

For example :

HyperDbg> !syscall script { print(@rax); } output {MyOutputName1 , MyOutputName2 , MyOutputName3}

You can specify up to 5 output sources in the default build of HyperDbg, but if you need more output sources for a single event, then you should compile HyperDbg with different configurations as described on Customize Build and change the DebuggerOutputSourceMaximumRemoteSourceForSingleEvent.

Starting from v0.10, HyperDbg supports modules (DLLs) as functions directly load DLLs and have the ability to forward events to functions. Note that, DLLs should be compiled into 64-bit binaries (32-bit binaries are not supported). Examples of DLLs are available in Rust and C++.

Generally, DLLs (in all low-level languages) should export a function with the name hyperdbg_event_forwarding with the first parameter as a pointer to the buffer message and the second parameter as an integer with the size that will be called by HyperDbg's event forwarding module once an event is triggered. The following example is the definition of the function in C/C++ (You can do the same in Rust, GO, etc.).

hyperdbg_event_forwarding(const char* buffer_message, unsigned int buffer_length);

After compiling the above function and exporting the above function (e.g., by using __declspec(dllexport)), you can open a module using the following command:

output create MyOutputName1 module C:\module\event_forwarding_module.dll

and after that, open it using the following command:

output open MyOutputName1

and then (same as above examples) you can pass the events using the following event:

!epthook nt!ExAllocatePoolWithTag script {
	printf("Pool allocation called!");
} output { MyOutputName1 }

In case, you want to see a list of sources, you can use the 'output' command without any parameter.

HyperDbg> output
1  file        not opened       MyOutputName1
2  file        opened           MyOutputName2
3  file        not opened       MyOutputName3

IOCTL

None

Remarks

You can use this command to forward the scripts' results from all the events.

You cannot use event forwarding in the immediate messaging mode in events (imm no).

Requirements

None

Related

Event Forwarding