huntrule

Cisco ASA WebVPN Proxy GET Requests to MacTunnel and csvrloader Paths

Alerts on proxy-observed HTTP GET requests to specific Cisco ASA WebVPN exploit-related URI stems.

FreeReviewedSigma · High · v5
Category
proxy
Author
Swachchhanda Shrawan Poudel (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2025-11-20
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Initial Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule identifies suspicious HTTP GET requests observed in proxy logs targeting Cisco ASA WebVPN resources, specifically MacTunnelStart.jar and csvrloader64.cab/csvrloader.jar paths. Such requests are consistent with exploitation activity against the ASA WebVPN interface because they access scriptable loader components. Detection relies on proxy telemetry capturing HTTP method (GET) and the requested URI stem values.

Reporting behind it

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Possible TP-Link Command Injection via WlanNetworkRpm Endpoint (via webserver)
Cisco ASA WebVPN Proxy GET Requests to MacTunnel and csvrloader Paths
Pivot detection · T1190 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. v1
    No changelog recorded for this version.2026-07-30

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