Detect Dynamic-link Library Injection in Google Chronicle
Adversaries may inject dynamic-link libraries (DLLs) into processes in order to evade process-based defenses as well as possibly elevate privileges. DLL injection is commonly performed by writing the path to a DLL in the virtual address space of the target process before loading the DLL by invoking a new thread. The write can be performed with native Windows API calls such as VirtualAllocEx and WriteProcessMemory, then invoked with CreateRemoteThread (which calls the LoadLibrary API responsible for loading the DLL). Variations include reflective DLL injection (self-mapping DLL), memory module loading, and Module Stomping/DLL Hollowing where a legitimate DLL is loaded then its AddressOfEntryPoint is overwritten before execution.
MITRE ATT&CK
- Technique
- T1055 Process Injection
- Sub-technique
- T1055.001 Dynamic-link Library Injection
- Canonical reference
- https://attack.mitre.org/techniques/T1055/001/
YARA-L Detection Query
rule dll_injection_createremotethread {
meta:
author = "df00tech"
description = "Detects DLL injection via CreateRemoteThread from suspicious injector processes followed by non-standard DLL load in target process"
severity = "HIGH"
mitre_attack = "T1055.001"
reference = "https://attack.mitre.org/techniques/T1055/001/"
events:
$inj.metadata.event_type = "PROCESS_INJECTION"
re.regex($inj.principal.process.file.full_path,
`(?i)(rundll32|regsvr32|mshta|wscript|cscript|powershell|cmd)\.exe`)
not re.regex($inj.principal.process.file.full_path,
`(?i)(MsMpEng|csrss\.exe|services\.exe|lsass\.exe)`)
$inj.target.process.file.full_path != ""
$inj.principal.hostname = $load.principal.hostname
$load.metadata.event_type = "PROCESS_MODULE_LOAD"
not re.regex($load.target.file.full_path,
`(?i)^(c:\\windows\\system32|c:\\windows\\syswow64|c:\\program files)`)
$load.target.file.full_path != ""
match:
$inj.principal.hostname over 1m
condition:
#inj > 0 and #load > 0
}Chronicle YARA-L 2.0 rule that correlates PROCESS_INJECTION UDM events from known-abused injector processes with PROCESS_MODULE_LOAD events for DLLs outside of trusted system directories. Both events must occur on the same host within a 1-minute window.
Data Sources
Required Tables
False Positives & Tuning
- Chronicle UDM normalization may map legitimate COM out-of-process server activation and DDE communication to PROCESS_INJECTION, generating false positives in heavily Office-automated environments
- Software updaters, crash reporters (Breakpad, WER), and diagnostic agents that inject tracing DLLs from vendor-specific subdirectories under ProgramData will match the DLL path filter
- JVM and CLR runtime environments perform cross-process memory operations during just-in-time compilation and remote profiling that may normalize to PROCESS_INJECTION in UDM
Other platforms for T1055.001
Testing Methodology
Validate this detection against 3 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 1DLL Injection via mavinject.exe (LOLBAS)
Expected signal: Sysmon Event ID 1: Process Create for mavinject.exe with CommandLine containing /INJECTRUNNING. Sysmon Event ID 8: CreateRemoteThread from mavinject.exe targeting notepad.exe. Sysmon Event ID 7: ImageLoad of amsi.dll in notepad.exe process.
- Test 2Reflective DLL Injection via PowerSploit Invoke-DllInjection
Expected signal: Sysmon Event ID 1: PowerShell process creation. Sysmon Event ID 3: Network connection to raw.githubusercontent.com. Sysmon Event ID 8: CreateRemoteThread from PowerShell to notepad.exe. PowerShell ScriptBlock Log Event ID 4104 with Invoke-DllInjection content.
- Test 3CreateRemoteThread DLL Injection via C# Executable
Expected signal: Sysmon Event ID 1: Process Create for csc.exe (C# compiler) spawned by PowerShell. Sysmon Event ID 1: injector_test.exe execution. Sysmon Event ID 11: File Create for injector_test.exe in TEMP. If full injection is performed: Sysmon Event ID 8 for CreateRemoteThread.
References (7)
- https://attack.mitre.org/techniques/T1055/001/
- https://www.endgame.com/blog/technical-blog/ten-process-injection-techniques-technical-survey-common-and-trending-process
- https://www.endgame.com/blog/technical-blog/hunting-memory
- https://blog.f-secure.com/hiding-malicious-code-with-module-stomping/
- https://www.ired.team/offensive-security/code-injection-process-injection/modulestomping-dll-hollowing-shellcode-injection
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1055.001/T1055.001.md
- https://lolbas-project.github.io/lolbas/Binaries/Mavinject/
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