Detect Masquerade File Type in IBM QRadar
Adversaries may masquerade malicious payloads as legitimate files through changes to the payload's formatting, including the file's signature, extension, icon, and contents. Various file types have a typical standard format, including how they are encoded and organized. For example, a file's signature (also known as header or magic bytes) is the beginning bytes of a file and is often used to identify the file's type. Adversaries may edit the header's hex code and/or the file extension of a malicious payload in order to bypass file validation checks and/or input sanitization. This behavior is commonly used when payload files are transferred and stored so that adversaries may move their malware without triggering detections. Polyglot files, which function differently based on the application that executes them, may also be used to disguise malicious capabilities.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1036 Masquerading
- Sub-technique
- T1036.008 Masquerade File Type
- Canonical reference
- https://attack.mitre.org/techniques/T1036/008/
QRadar Detection Query
SELECT DATEFORMAT(devicetime, 'yyyy-MM-dd HH:mm:ss') AS event_time,
logsourceid,
LOGSOURCENAME(logsourceid) AS log_source,
sourceip,
username,
"filename",
"filepath",
"processname",
"commandline",
QIDNAME(qid) AS event_name
FROM events
WHERE LOGSOURCETYPEID(logsourceid) = 12 /* Microsoft Windows Security Event Log */
AND qid IN (SELECT id FROM qidmap WHERE name LIKE '%Sysmon%' OR name LIKE '%File Create%')
AND devicetime > (NOW() - 86400000)
AND (
LOWER("filename") LIKE '%.gif'
OR LOWER("filename") LIKE '%.jpg'
OR LOWER("filename") LIKE '%.jpeg'
OR LOWER("filename") LIKE '%.png'
OR LOWER("filename") LIKE '%.bmp'
OR LOWER("filename") LIKE '%.txt'
OR LOWER("filename") LIKE '%.pdf'
OR LOWER("filename") LIKE '%.mp3'
OR LOWER("filename") LIKE '%.pub'
OR LOWER("filename") LIKE '%.accdb'
)
AND (
LOWER("processname") LIKE '%powershell.exe'
OR LOWER("processname") LIKE '%cmd.exe'
OR LOWER("processname") LIKE '%wscript.exe'
OR LOWER("processname") LIKE '%cscript.exe'
OR LOWER("processname") LIKE '%mshta.exe'
OR LOWER("processname") LIKE '%certutil.exe'
OR LOWER("processname") LIKE '%bitsadmin.exe'
OR LOWER("processname") LIKE '%rundll32.exe'
)
ORDER BY devicetime DESC
LIMIT 500AQL query correlating Sysmon file creation events (EventID 11) ingested via Windows DSM against suspicious LOLBin process names writing files with media or document extensions. Targets the last 24 hours and returns the process, filename, and source context for analyst triage.
Data Sources
Required Tables
False Positives & Tuning
- Helpdesk or deployment scripts using certutil.exe or bitsadmin.exe to stage software packages with non-executable intermediate file names
- PowerShell-based backup agents that write compressed or encoded blobs with image-like extensions as part of delta backup formats
- Document management automation using wscript.exe or cmd.exe to batch-rename or convert files into PDF/DOC intermediates
Other platforms for T1036.008
Testing Methodology
Validate this detection against 4 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 1Masquerade EXE as GIF File (Volt Typhoon Pattern)
Expected signal: Sysmon Event ID 11: FileCreate with TargetFilename 'data_export.gif'. The file hash will match calc.exe despite the .gif extension. DeviceFileEvents with FileName=data_export.gif, ActionType=FileCreated, InitiatingProcessFileName=cmd.exe.
- Test 2Create Polyglot HTML/DLL File (StrelaStealer Pattern)
Expected signal: Sysmon Event ID 11: FileCreate with TargetFilename 'invoice_polyglot.html'. Sysmon Event ID 1: Process Create for powershell.exe with Set-Content command. PowerShell ScriptBlock Log Event ID 4104 with the polyglot content creation.
- Test 3Rename DLL to Image Extension
Expected signal: Sysmon Event ID 11: FileCreate with TargetFilename 'screenshot.png' in Temp directory. File hash will match version.dll. DeviceFileEvents with FileName=screenshot.png created by cmd.exe.
- Test 4Certutil Download with Extension Masquerade
Expected signal: Sysmon Event ID 1: Process Create for certutil.exe with '-encode' in CommandLine. Sysmon Event ID 11: FileCreate with TargetFilename 'payload.txt'. DeviceProcessEvents with ProcessCommandLine containing 'certutil -encode'.
References (7)
- https://attack.mitre.org/techniques/T1036/008/
- https://unit42.paloaltonetworks.com/polyglot-file-icedid-payload
- https://www.secureworks.com/research/bronze-silhouette-targets-us-government-and-defense-organizations
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-devicefileevents-table
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1036.008/T1036.008.md
- https://www.withsecure.com/en/research/publications/kapeka
- https://www.netskope.com/blog/lumma-stealer
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