Detect Shared Modules in Sumo Logic CSE
Adversaries may execute malicious payloads by loading shared modules into running processes. Shared modules are executable files (DLLs on Windows, .so on Linux, .dylib on macOS) loaded at runtime to provide reusable code or access OS API functions. Adversaries abuse this by loading malicious shared objects from arbitrary local paths or UNC network paths, allowing payload execution within the memory space of a legitimate host process. Windows uses LoadLibrary/LoadLibraryEx (via NTDLL.dll Native API), Linux uses dlopen/dlsym from dlfcn.h, and macOS uses both dlopen and Objective-C runtime calls. This technique enables modular malware architectures where the main dropper loads additional capability modules — seen in gh0st RAT, Astaroth, RotaJakiro, FoggyWeb, and BLINDINGCAN.
MITRE ATT&CK
- Tactic
- Execution
- Technique
- T1129 Shared Modules
- Canonical reference
- https://attack.mitre.org/techniques/T1129/
Sumo Detection Query
_sourceCategory=windows/sysmon EventCode=7
| parse "<ImageLoaded>*</ImageLoaded>" as ImageLoaded nodrop
| parse "<Image>*</Image>" as LoaderProcess nodrop
| parse "<Signed>*</Signed>" as Signed nodrop
| parse "<SignatureStatus>*</SignatureStatus>" as SignatureStatus nodrop
| parse "<Hashes>*</Hashes>" as Hashes nodrop
| parse "<CommandLine>*</CommandLine>" as CommandLine nodrop
| parse "<User>*</User>" as User nodrop
| where toLowerCase(ImageLoaded) matches "*.dll"
| eval ImageLower = toLowerCase(ImageLoaded)
| eval ProcessLower = toLowerCase(LoaderProcess)
| eval IsTempPath = if(ImageLower matches "*\\appdata\\local\\temp\\*" OR ImageLower matches "*\\appdata\\roaming\\*" OR ImageLower matches "*\\windows\\temp\\*" OR ImageLower matches "*\\users\\public\\*" OR ImageLower matches "c:\\temp\\*" OR ImageLower matches "c:\\tmp\\*" OR ImageLower matches "*\\downloads\\*", 1, 0)
| eval IsUNCPath = if(ImageLower matches "\\\\*", 1, 0)
| eval IsSuspiciousLoader = if(ProcessLower matches "*\\rundll32.exe" OR ProcessLower matches "*\\regsvr32.exe" OR ProcessLower matches "*\\mshta.exe" OR ProcessLower matches "*\\wscript.exe" OR ProcessLower matches "*\\cscript.exe" OR ProcessLower matches "*\\msbuild.exe" OR ProcessLower matches "*\\installutil.exe", 1, 0)
| eval IsKnownGoodDir = if(ImageLower matches "*\\windows\\system32\\*" OR ImageLower matches "*\\windows\\syswow64\\*" OR ImageLower matches "*\\windows\\winsxs\\*" OR ImageLower matches "*\\program files\\*", 1, 0)
| eval IsUnsigned = if(Signed = "false" OR Signed = "", 1, 0)
| eval SuspicionScore = IsTempPath + IsUNCPath + (IsSuspiciousLoader * (1 - IsKnownGoodDir)) + IsUnsigned
| where SuspicionScore >= 1 AND IsKnownGoodDir = 0
| fields _messageTime, _sourceHost, User, LoaderProcess, CommandLine, ImageLoaded, Signed, SignatureStatus, Hashes, IsTempPath, IsUNCPath, IsSuspiciousLoader, IsUnsigned, SuspicionScore
| sort by SuspicionScore, _messageTimeSumo Logic CSE query detecting T1129 shared module abuse via Sysmon Event ID 7 (Image Loaded). Parses XML Sysmon events to evaluate DLL load paths against suspicious directories, UNC paths, and known LOLBin loader processes. Computes a suspicion score to prioritize high-confidence events while suppressing known-good system directory loads.
Data Sources
Required Tables
False Positives & Tuning
- Managed software deployment via PDQ Deploy, Ansible, or similar tools that temporarily place DLLs in staging directories accessible to running processes before installation completes
- Browser extension or plugin frameworks (e.g., legacy NPAPI plugins, COM add-ins) that load shared libraries from user-profile locations as part of sandboxed execution
- Penetration testing or red team tooling run by authorized staff loading reflective DLLs from temp directories during sanctioned assessments
Other platforms for T1129
Testing Methodology
Validate this detection against 5 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Load DLL from Temp Directory via rundll32
Expected signal: Sysmon Event ID 7 (ImageLoad): ImageLoaded path will be %TEMP%\df00tech-test-module.dll, Image will be C:\Windows\System32\rundll32.exe. Sysmon Event ID 1 (Process Create): rundll32.exe with command line containing the Temp path. Security Event ID 4688 if command line auditing is enabled.
- Test 2Load DLL via PowerShell Assembly.LoadFile from AppData
Expected signal: Sysmon Event ID 7: ImageLoaded will show AppData\Roaming\df00tech-module.dll loaded by powershell.exe. Sysmon Event ID 1: PowerShell process creation with LoadFile command. Sysmon Event ID 11: File creation of df00tech-module.dll in AppData\Roaming.
- Test 3Load Shared Object from /tmp via dlopen on Linux
Expected signal: Auditd syscall events: openat(2) call to /tmp/df00tech_test_module.so from python3 process. Linux audit event type=EXECVE for gcc and python3. If using Falco or Sysdig: proc.name=python3 with fd.name=/tmp/*.so triggers shared lib load from tmp rule. Syslog entry if auditd is configured to monitor /tmp for file opens.
- Test 4Regsvr32 Loading Unregistered DLL from User-Writable Path
Expected signal: Sysmon Event ID 7 (ImageLoad): ImageLoaded=C:\Windows\Temp\df00tech-reg-test.dll, Image=C:\Windows\System32\regsvr32.exe. Sysmon Event ID 1: regsvr32.exe with /s flag and the temp path. The /s flag suppresses the dialog box — this silence flag is itself a behavioral indicator used in malware deployment.
- Test 5Load dylib from /tmp on macOS via Python ctypes
Expected signal: macOS Endpoint Security Framework: ES_EVENT_TYPE_NOTIFY_MMAP event for the dylib mmap into python3 process address space. Unified log (log stream --predicate 'subsystem == "com.apple.dyld"') shows dylib load from /tmp. If Jamf Protect or CrowdStrike Falcon is deployed: 'Shared Library Loaded from /tmp' detection fires.
References (10)
- https://attack.mitre.org/techniques/T1129/
- https://learn.microsoft.com/troubleshoot/windows-client/deployment/dynamic-link-library
- https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/DynamicLibraries/100-Articles/OverviewOfDynamicLibraries.html
- https://tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html
- https://blog.netlab.360.com/stealth_rotajakiro_backdoor_en/
- https://unit42.paloaltonetworks.com/unit42-new-improved-macos-backdoor-oceanlotus/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1129/T1129.md
- https://learn.microsoft.com/en-us/sysinternals/downloads/sysmon
- https://github.com/SigmaHQ/sigma/tree/master/rules/windows/image_load
- https://www.elastic.co/guide/en/security/current/prebuilt-rules.html
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