EventPairHandles

An EventPair Object is an event constructed by two _KEVENT structures which are conventionally named High and Low.

There is a relation between generic Event Objects and Debuggers because they must create a custom event called DebugEvent able to handle exceptions. Due to the presence of events owned by the Debugger, every information relative to the events of a normal process differs from a debugged process.

Technique Identifier

U0116

Technique Tag

EventPairHandles

Evasion Categories

Anti-Debugging

Code Snippets

#define WIN32_LEAN_AND_MEAN
#include <stdio.h>
#include <iostream>
#include <stdlib.h>
#include <windows.h>
#include "defs.h"


#pragma comment(lib,"ntdll.lib")
#pragma comment(lib,"psapi.lib")


void QueryProcessHeapMethod(void)
{
    PDEBUG_BUFFER buffer;
    buffer = RtlCreateQueryDebugBuffer(0,FALSE);
    RtlQueryProcessHeapInformation(buffer);

    if (buffer->RemoteSectionBase == (PVOID) 0x50000062){
        MessageBoxA(NULL,"Debugged","Warning",MB_OK);
    }
    else {
        MessageBoxA(NULL,"Not Debugged","Warning",MB_OK);
    }
    if (buffer->EventPairHandle == (PVOID) 0x00002b98) {
        MessageBoxA(NULL,"Debugged","Warning",MB_OK);
    }
    else {
        MessageBoxA(NULL,"Not Debugged","Warning",MB_OK);
        printf("EventPairHandle= %x",(int)buffer->EventPairHandle);
    }
}
int main()
{
    QueryProcessHeapMethod();
    return (EXIT_SUCCESS);
}

About Author Open Snippet

Author: Unprotect / Target Platform: Windows

Detection Rules

rule Detect_EventPairHandles: AntiDebug {
    meta: 
        description = "Detect EventPairHandlesas anti-debug"
        author = "Unprotect"
        comment = "Experimental rule"
    strings:
        $1 = "EventPairHandles" fullword ascii
        $2 = "RtlCreateQueryDebugBuffer" fullword ascii
        $3 = "RtlQueryProcessHeapInformation" fullword ascii
    condition:   
       uint16(0) == 0x5A4D and filesize < 1000KB and 2 of them 
}

Additional Resources

External Links

The resources provided below are associated links that will give you even more detailed information and research on current evasion technique. It is important to note that, while these resources may be helpful, it is important to exercise caution when following external links. As always, be careful when clicking on links from unknown sources, as they may lead to malicious content.

https://www.evilfingers.com/publications/research_EN/EventPairsHandle.pdf

Matching Samples 10 most recent

Sample Name	Matching Techniques	First Seen	Last Seen
al-khaser.exe	24	2024-11-13	1 year, 4 months ago

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Created

March 18, 2019

Last Revised

March 24, 2026