Suspicious Encoded PowerShell DownloadString Execution
- Product
- windows
- Category
- process_creation
- Author
- HuntRule
- Published
- 2026-09-28
- Updated
- 2026-09-28
ATT&CK techniques
Execution → C2Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
Exfiltration
Impact
What it detects
This rule detects PowerShell using encoded command flags or an in-memory WebClient DownloadString with Invoke-Expression, the loader behavior in the Confluence CVE-2023-22518 to Cerber ransomware chain. Encoded and download-and-execute PowerShell is a common obfuscated fileless delivery method preceding ransomware deployment.
Reporting behind it
- huntress.comhttps://www.huntress.com/blog/confluence-to-cerber-exploitation-of-cve-2023-22518-for-ransomware-deployment
- attack.mitre.orghttps://attack.mitre.org/techniques/T1059/001/
- attack.mitre.orghttps://attack.mitre.org/techniques/T1027/010/
- attack.mitre.orghttps://attack.mitre.org/techniques/T1105/
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
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