!ioin (hook IN instruction execution)

Description of '!ioin' command in HyperDbg.

Command

!ioin

Syntax

!ioin [port (hex value)] [pid (hex value)] [core (hex value)] [imm (yes|no)] [event options]

Description

Triggers when the debugging machine executes IN or IN* instructions or, in other words, when Windows or a driver tries to use I/O ports.

When you enable this event, only your specific I/O port will be hooked, so this command won't trigger on all I/O ports, thus won't make your computer slow.

Parameters

[port (hex value)]

Trigger in the case of using a special I/O port. If you don't specify this parameter, then it will be triggered for all I/O ports.

[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 it's not real-time. By default, this value is set to yes.

[event options]

Regular event parameters that 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 port number that the target tries to access.

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 break on all accesses (IN/IN* instructions) to I/O ports.

HyperDbg> !ioin

If we want to break on I/O port 0x3f8.

HyperDbg> !ioin 0x3f8

Note that default ports for serial connections are: 0x03f8, 0x02f8, 0x03e8, 0x02e8.

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> !ioin 0x3f8 script { HyperDbg Script Here }

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

HyperDbg> !ioin 0x3f8 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> !ioin 0x3f8 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)

Monitoring execution of IN/IN* instructions for I/O port 0x3f8 and run 3 nops whenever the event is triggered. Take a look at Run Custom Code for more information.

HyperDbg> !ioin 0x3f8 code {90 90 90}

Run Custom Code (Conditional)

Monitoring execution of IN/IN* instructions for I/O port 0x3f8 and run 3 nops whenever the event condition is triggered and run 3 nops whenever the event is triggered. Take a look at Run Custom Code and how to create a condition for more information.

HyperDbg> !ioin 0x3f8 code {90 90 90} condition {90 90 90}

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

IOCTL

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

As EventType use IN_INSTRUCTION_EXECUTION and send the special I/O port (if any) if you want to monitor just an I/O port in OptionalParam1 in DEBUGGER_GENERAL_EVENT_DETAIL.

Design

Both !ioin and !ioout use the vm-exits caused by setting bits in the I/O Bitmap (I/O Bitmap A, I/O Bitmap B) field of the hypervisor VMCS.

For emulating I/O ports, vm-exit with (EXIT_REASON_IO_INSTRUCTION) or exit-reason 30 is used.

Remarks

You can also modify the content of I/O ports for both IN and OUT instructions.

This is an event command, but in the current version of HyperDbg (in Debugger Mode), this command will continue the debuggee for some time; however, you can use this trick to make sure you won't lose any event.

Requirements

None

!ioout (hook OUT instruction execution)