Detect LiteSpeed cPanel Plugin UNIX Symbolic Link (Symlink) Following Vulnerability in Sumo Logic CSE
Detects exploitation of CVE-2026-54420, a UNIX symbolic link (symlink) following vulnerability in the LiteSpeed cPanel Plugin. Attackers with local access can create malicious symlinks to read or overwrite files outside the intended directory, potentially leading to privilege escalation or unauthorized file access on cPanel-managed hosting servers. This vulnerability is actively exploited in the wild (CISA KEV).
MITRE ATT&CK
Sumo Detection Query
_sourceCategory=linux/audit OR _sourceCategory=linux/syslog OR _sourceCategory=endpoint/linux
| parse regex "(?<raw_cmd>(?:ln\s+-s|symlink|symlinkat)[^\n]*)"
| where !isNull(raw_cmd)
| if (raw_cmd matches /(?i)(lsws|lsphp|litespeed|cpanel.plugin|\/usr\/local\/lsws|\/var\/lsws|\/etc\/lsws)/, 1, 0) as litespeed_context
| if (raw_cmd matches /(?i)(\/etc\/passwd|\/etc\/shadow|\/root\/|\/etc\/ssh|\/etc\/sudoers|\/proc\/)/, 1, 0) as sensitive_target
| where litespeed_context = 1 OR sensitive_target = 1
| fields _messageTime, _sourceHost, _sourceCategory, raw_cmd, litespeed_context, sensitive_target
| sort by _messageTime desc
| count by _sourceHost, litespeed_context, sensitive_target
| sort by _count descSumo Logic query parsing Linux audit and syslog data for symlink operations tied to LiteSpeed plugin paths or sensitive file targets, with field extraction and aggregation by host.
Data Sources
Required Tables
False Positives & Tuning
- Automated cPanel plugin update jobs run by hosting provider maintenance windows
- LiteSpeed LSWS installer creating PHP symlinks during initial setup or version upgrades
- cPanel-initiated scripts that modify LiteSpeed configuration and create symlinks for PHP SAPI selection
- Penetration testing engagements against cPanel environments with prior authorization
Other platforms for CVE-2026-54420
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 1Create Malicious Symlink in LiteSpeed Plugin Directory Targeting /etc/shadow
Expected signal: auditd SYSCALL=symlink with a1 pointing to /etc/shadow; FileOpenInfo event on /etc/shadow via the symlink path; process creating the symlink is a non-root user
- Test 2Symlink Traversal via LiteSpeed Binary Process Simulation
Expected signal: SYSCALL=symlink event for the ln -sv command; stat and readlink syscalls on the symlink; auditd logs should capture the effective UID and process name
- Test 3Enumerate LiteSpeed Plugin Directory and Create Targeted Symlink Chain
Expected signal: Multiple syscall events: find spawning openat calls on LiteSpeed paths; SYSCALL=symlink for the ln command; readdir on /root/.ssh via the symlink (if permitted); auditd AVC denials if SELinux/AppArmor active
References (4)
- https://blog.litespeedtech.com/2026/06/01/security-update-for-litespeed-cpanel-plugin-2/
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-54420
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