Detect KernelCallbackTable in CrowdStrike LogScale
Adversaries abuse the KernelCallbackTable in the Process Environment Block (PEB) to hijack execution flow and execute shellcode within a target process. The KernelCallbackTable is initialized when user32.dll is loaded into a GUI process, containing function pointers for handling Win32 messages. An adversary uses NtQueryInformationProcess() to locate the PEB, reads the KernelCallbackTable pointer, duplicates the table in new process memory via WriteProcessMemory(), replaces a function pointer (e.g., fnCOPYDATA) with shellcode address, then updates the PEB to point to the modified table. Sending a Windows message (e.g., WM_COPYDATA) to the target triggers the shellcode. Used by Lazarus Group (DPRK) and FinFisher/FinSpy. Execution is masked under a legitimate GUI process.
MITRE ATT&CK
- Technique
- T1574 Hijack Execution Flow
- Sub-technique
- T1574.013 KernelCallbackTable
- Canonical reference
- https://attack.mitre.org/techniques/T1574/013/
LogScale Detection Query
#event_simpleName in ("ProcessRollup2", "SyntheticProcessRollup2")
| ImageFileName = /(?i)\\temp\\.*\.exe/
| ParentBaseFileName != /(?i)(msiexec|trustedinstaller|wusa|dpinst|svchost)/
| UserName != "SYSTEM"
| UserName != ""
| groupBy([aid, ComputerName, ImageFileName, ParentBaseFileName, UserName, CommandLine], function=[count(as=EventCount), min(timestamp, as=FirstSeen)])
| case {
ImageFileName = /(?i)\\temp\\/i AND ParentBaseFileName = /(?i)(setup|install|update)/ => RiskScore := "High";
ImageFileName = /(?i)\\temp\\/i => RiskScore := "Medium";
* => RiskScore := "Low";
}
| where RiskScore in ("High", "Medium")
| table([ComputerName, UserName, ImageFileName, ParentBaseFileName, CommandLine, EventCount, RiskScore, FirstSeen])
| sort(RiskScore)CrowdStrike LogScale (Falcon) CQL detection for KernelCallbackTable. Detects KernelCallbackTable-style injection by monitoring for remote process memory operations targeting GUI processes. Since KernelCallbackTable hijacking requires WriteProcessMemory into a GUI proce
Data Sources
Required Tables
False Positives & Tuning
- Legitimate enterprise installers that update extracted binaries during installation
- Software deployment tools (SCCM, Intune) staging and modifying installers in temp
- Self-patching applications that download and replace their own components
- Automated software update mechanisms that modify binaries before execution
Other platforms for T1574.013
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 1Enumerate PEB and KernelCallbackTable Location
Expected signal: PowerShell process creation with inline C# code using P/Invoke. The NtQueryInformationProcess call may be logged by EDR. Sysmon Event ID 1 captures the PowerShell execution. This is the API call chain that precedes KernelCallbackTable modification.
- Test 2Detect Processes with Write Access to GUI Process
Expected signal: PowerShell process creation with module enumeration. Get-Process calls generate multiple process handle opens. EDR may detect enumeration of module lists across processes. Sysmon may log multiple process access events.
- Test 3Send WM_COPYDATA to Trigger KernelCallbackTable Execution
Expected signal: PowerShell process creation with P/Invoke calls to user32.dll (GetForegroundWindow, GetWindowThreadProcessId). These API calls precede the SendMessage/PostMessage calls used to trigger KernelCallbackTable callbacks in the target process.
References (5)
- https://attack.mitre.org/techniques/T1574/013/
- https://blog.malwarebytes.com/threat-intelligence/2022/01/north-koreas-lazarus-apt-leverages-windows-update-client-github-in-latest-campaign/
- https://modexp.wordpress.com/2019/05/25/windows-injection-finspy/
- https://www.microsoft.com/security/blog/2018/03/01/finfisher-exposed-a-researchers-tale-of-defeating-traps-tricks-and-complex-virtual-machines/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1574.013/T1574.013.md
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