Obfuscated VShell Bash Payload Execution via Base64-Decoded Filename (via process_creation)

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1059.004Unix Shell
Persistence
Priv Esc
Defense Evasion
- T1202Indirect Command Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects VShell first-stage execution where a crafted filename embeds a brace-expanded echo and base64 decode piped into bash, causing shell processing of a directory listing to run an attacker command. Adversaries leverage this indirect execution to hide a downloader inside a filename, making detection of the echo, base64 decode, and bash construct important for catching the initial foothold on Linux hosts.

Reporting behind it

Related detections9 linkedT1059.004 — drag to rearrange

Suspicious Indirect PowerShell Execution via Forfiles LOLBIN (via process_creation)

Possible OMIGOD Unauthenticated OMI WSMan Command Execution via Web Request (via webserver)

Malicious Curl to Shell Pipe Dropper Execution (via process_creation)

Malicious Shai-Hulud npm Worm Staging Script Execution on Linux

Suspicious Java Process Spawning Download or Shell Utility (Exposed JDWP Abuse)

Suspicious PostgreSQL Spawning Command Shell via COPY FROM PROGRAM (Soco404)

Suspicious Bash Reverse Shell via Dev TCP Redirection

Suspicious Linux Payload Fetch Piping curl Output Into a Shell

Possible CUPS cups-browsed Remote Code Execution via Shell Child Process

Obfuscated VShell Bash Payload Execution via Base64-Decoded Filename (via process_creation)

Pivot detection · T1059.004 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →