Detect Microsoft Windows Command Injection (CVE-2026-96951) in Sumo Logic CSE
Detects exploitation of CVE-2026-96951, a command injection vulnerability (CWE-77) in Microsoft Windows that is listed in the CISA Known Exploited Vulnerabilities catalog. Exploitation allows an attacker to inject and execute arbitrary operating-system commands via improperly neutralized special elements passed to a Windows component. This detection surfaces suspicious child-process chains, shell invocations with injected command separators/metacharacters, and anomalous process lineage consistent with active exploitation on unpatched hosts.
MITRE ATT&CK
- Tactic
- Initial Access Execution
Sumo Detection Query
_sourceCategory=*windows* ("cmd.exe" OR "powershell.exe" OR "pwsh.exe" OR "wscript.exe" OR "cscript.exe")
| parse "NewProcessName=*\"" as process nodrop
| parse "ParentProcessName=*\"" as parent nodrop
| parse "CommandLine=*\"" as cmd nodrop
| where (toLowerCase(parent) matches "*svchost.exe" or toLowerCase(parent) matches "*spoolsv.exe" or toLowerCase(parent) matches "*w3wp.exe" or toLowerCase(parent) matches "*wsmprovhost.exe")
| where cmd matches /[&|;`]|&&|\|\||\$\(|%0a/
| where cmd matches /(?i)(whoami|certutil|bitsadmin|curl|Invoke-WebRequest|-enc|FromBase64String|rundll32|regsvr32)/
| fields _messageTime, host, parent, process, cmd
| sort by _messageTime descSumo Logic search isolating shells launched by Windows service hosts with injected metacharacters and recon/download tooling for CVE-2026-96951.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate chained admin commands
- Patch management shell activity
- IIS application automation
Other platforms for CVE-2026-96951
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 1 Shell command chaining via metacharacter injection
Expected signal: Sysmon EventID 1 / Security 4688 showing cmd.exe with a command line containing '&' separators and whoami/net invocations.
- Test 2 PowerShell encoded command via pipe injection
Expected signal: Process-creation event for powershell.exe with command line containing '|' and '-enc' with a base64 blob.
- Test 3 Service-host spawned download via certutil
Expected signal: cmd.exe process with '&&' chaining and a certutil child process performing a URL download.
Response Playbook
Triage
- Confirm the host's Windows patch level against the MSRC advisory for CVE-2026-96951; determine whether the relevant October 2026 security update is installed.
- Reconstruct the full process tree for the alerting event: identify the injecting parent process, the spawned shell, and any grandchild processes, capturing full command lines and user context.
- Examine the injected command-line content to determine intent (reconnaissance, download, persistence) and whether metacharacters indicate successful injection versus benign chaining.
- Check whether the initiating service process (e.g., svchost, spoolsv, w3wp) is network-facing and had recent inbound connections correlating with the exploitation timestamp.
Containment
- Network-isolate the affected host via EDR to halt any attacker command-and-control or lateral movement.
- Suspend or kill the malicious process tree and disable the compromised service account pending investigation.
- Apply the vendor patch for CVE-2026-96951 or the MSRC-recommended workaround to all vulnerable hosts in the environment.
Evidence Collection
- Preserve process-creation logs (Sysmon EventID 1 / Security 4688), EDR process telemetry, and command-line history for the affected host.
- Capture memory and disk forensic images of the compromised host before remediation, and collect any files dropped by certutil/bitsadmin/curl downloads.
Escalation Criteria
- !Escalate to incident response if the injected commands achieved SYSTEM-level execution, downloaded second-stage payloads, or established persistence.
- !Escalate to threat-intel and leadership if multiple hosts show the same injection pattern, indicating active campaign exploitation of this KEV vulnerability.
Investigation Guide
Related Techniques
Forensic Artifacts
- >
Sysmon EventID 1 / Security 4688 process-creation records showing anomalous parent-child lineage - >
Command-line arguments containing shell metacharacters captured in EDR process telemetry - >
Files written to disk by certutil, bitsadmin, or curl invoked through the injected command - >
Windows Prefetch and ShimCache entries for shells spawned by service hosts
Tuning Guidance
Establish a baseline of legitimate service hosts that routinely spawn shells (deployment agents, backup tooling, IIS automation) and exclude those specific parent/command-line pairs. Tighten the recon/download keyword list to your environment's observed attacker tooling, and raise severity when the spawned shell writes executables or initiates outbound connections. Review exclusions after any patch deployment or application change.
Hunting Queries
Baselines shell interpreters spawned by non-interactive Windows service hosts carrying command-separator metacharacters, surfacing candidate command-injection attempts for review.
DeviceProcessEvents | where InitiatingProcessFileName in~ ("svchost.exe","spoolsv.exe","w3wp.exe","wsmprovhost.exe") | where FileName in~ ("cmd.exe","powershell.exe","pwsh.exe") | where ProcessCommandLine has_any ("&","|",";","`","$(") | project Timestamp, DeviceName, InitiatingProcessFileName, FileName, ProcessCommandLineindex=windows (EventCode=1 OR EventCode=4688) | eval parent=lower(coalesce(ParentImage,Creator_Process_Name)) | search (parent="*svchost.exe" OR parent="*spoolsv.exe" OR parent="*w3wp.exe") (CommandLine="*cmd.exe*" OR CommandLine="*powershell*") | regex CommandLine="[&|;`]|\$\(" | table _time host parent CommandLineAtomic Red Team Tests
Simulates command injection by chaining a benign recon command onto a shell invocation using the & separator, mirroring exploitation telemetry of CVE-2026-96951.
Command
cmd.exe /c "echo input & whoami & net user"Cleanup
echo No cleanup required; commands are read-only recon.Expected Telemetry
Sysmon EventID 1 / Security 4688 showing cmd.exe with a command line containing '&' separators and whoami/net invocations.
Expected Detection
The kql/spl queries match on cmd.exe command line containing '&' metacharacter plus 'whoami' and 'net ' tooling.
Simulates injection of a base64-encoded PowerShell payload chained through a pipe, emulating download/execute behavior post-injection.
Command
powershell.exe -Command "echo input | powershell -enc ZQBjAGgAbwAgAHQAZQBzAHQA"Cleanup
echo No cleanup required; payload only echoes text.Expected Telemetry
Process-creation event for powershell.exe with command line containing '|' and '-enc' with a base64 blob.
Expected Detection
Queries match on powershell.exe command line containing '|' metacharacter and '-enc' tooling indicator.
Simulates a follow-on download invoked through an injected command from a shell, using certutil to fetch a remote file as attackers commonly do after command injection.
Command
cmd.exe /c "ping 127.0.0.1 && certutil -urlcache -split -f http://127.0.0.1/test.txt %TEMP%\test.txt"Cleanup
del /q %TEMP%\test.txtExpected Telemetry
cmd.exe process with '&&' chaining and a certutil child process performing a URL download.
Expected Detection
Queries match on cmd.exe command line containing '&&' metacharacter and 'certutil' download tooling.