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Unlock with Pro - from £29/user/moDetect LaunchServer FileServerHandler Unauthenticated Path Traversal (CVE-2026-54617) in Sumo Logic CSE
Detects exploitation attempts against pro.gravit.launcher:launchserver-api's FileServerHandler, which is vulnerable to an unauthenticated path traversal (CWE-22) allowing arbitrary file read (CWE-200) and disclosure of sensitive data such as credentials or keys (CWE-522) in versions <= 5.7.11. Attackers send crafted HTTP requests containing traversal sequences (../, encoded variants, absolute paths) to the LaunchServer file-serving endpoint to read files outside the intended web root, including server configs, private keys, and auth databases.
MITRE ATT&CK
- Tactic
- Initial Access Collection
Sumo Detection Query
_sourceCategory=*web* OR _sourceCategory=*proxy*
| parse "* * * \"* * *\" * *" as clientip, ident, user, method, uri, protocol, status, size
| where uri matches "*FileServerHandler*"
| where uri matches "*..%2f*" or uri matches "*..%5c*" or uri matches "*../*" or uri matches "*%2e%2e%2f*" or uri matches "*..%c0%af*"
| count by clientip, uri, status
| sort -_countSearches web access logs for traversal payloads sent to the LaunchServer FileServerHandler endpoint, indicating attempted exploitation of CVE-2026-54617.
Data Sources
Required Tables
False Positives & Tuning
- Scanner or crawler traffic with encoded paths
- Legitimate mod file requests containing dot characters
- Log parsing artifacts from malformed URIs
Other platforms for CVE-2026-54617
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 1Basic path traversal against FileServerHandler
Expected signal: Web/proxy access log entry showing GET request to FileServerHandler with '../' sequences and response body containing /etc/passwd content or a 200 status.
- Test 2URL-encoded traversal against FileServerHandler
Expected signal: Access log entry with percent-encoded traversal sequences in the request URI/query targeting FileServerHandler.
- Test 3Windows-style backslash traversal against FileServerHandler
Expected signal: IIS/web log entry showing a request to FileServerHandler containing '..%5c' sequences and an unusual response size for win.ini content.
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