Detect Google Skia Out-of-Bounds Write (CVE-2026-3909) in Splunk
Detects exploitation attempts targeting CVE-2026-3909, an out-of-bounds write vulnerability in Google Skia graphics library. Skia is embedded in Chrome and other Google products. Exploitation can lead to arbitrary code execution via crafted web content or malicious files. This vulnerability is confirmed exploited in the wild (CISA KEV).
MITRE ATT&CK
- Tactic
- Initial Access Execution
SPL Detection Query
index=endpoint sourcetype=crowdstrike:events:sensor OR sourcetype=sysmon
| where (ParentImage IN ("*\\chrome.exe", "*\\msedge.exe", "*\\brave.exe", "*\\opera.exe")
AND Image IN ("*\\cmd.exe", "*\\powershell.exe", "*\\wscript.exe", "*\\cscript.exe", "*\\mshta.exe", "*\\rundll32.exe", "*\\regsvr32.exe"))
OR (process_name IN ("chrome.exe", "msedge.exe") AND dest_port IN (4444, 1337, 8080, 9001))
| eval risk_indicator=case(
match(Image, "(?i)(cmd|powershell)\.exe"), "ShellSpawnedFromBrowser",
isnotnull(dest_port), "SuspiciousOutboundPort",
1=1, "GenericSuspicious"
)
| table _time, host, user, ParentImage, ParentCommandLine, Image, CommandLine, dest_ip, dest_port, risk_indicator
| sort -_timeDetects Skia exploit post-exploitation: Chromium-family browsers spawning shell interpreters or making high-risk outbound connections.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Browser-launched installer or update helper processes
- Security testing tools running from browser context
- Legitimate enterprise management software using high-number ports
Other platforms for CVE-2026-3909
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 1Simulate Browser Spawning Shell (Windows)
Expected signal: Sysmon Event ID 1 showing cmd.exe with ParentImage containing chrome.exe; Windows Security 4688 process creation log
- Test 2Simulate Suspicious Outbound Network Connection from Browser Process (Linux)
Expected signal: Auditd or Sysmon-for-Linux network connection event showing process named 'chrome' connecting to port 4444
- Test 3Simulate Renderer Sandbox Escape via LOLBin Execution (Windows)
Expected signal: Sysmon Event ID 1 with regsvr32.exe CommandLine containing /i:http and scrobj.dll; Sysmon Event ID 3 network connection from regsvr32.exe
- Test 4Skia OOB Write Crash Reproduction (macOS — Lab Only)
Expected signal: Chrome crash report generated in crash-dumps-dir; macOS Console logs show SIGSEGV or SIGABRT from renderer process
Unlock Pro Content
Get the full detection package for CVE-2026-3909 including response playbook, investigation guide, and atomic red team tests.