Detect LiteSpeed cPanel Plugin UNIX Symbolic Link (Symlink) Following Vulnerability in Elastic Security
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
Elastic Detection Query
sequence by host.name, user.name with maxspan=5m
[file where event.action in ("creation", "change") and
file.type == "symlink" and
(
file.path like~ "/usr/local/lsws/*" or
file.path like~ "/opt/cpanel/*" or
file.path like~ "/var/lsws/*" or
file.path like~ "/etc/lsws/*"
)]
[file where event.action in ("creation", "change", "access") and
(
file.path like~ "/etc/passwd" or
file.path like~ "/etc/shadow" or
file.path like~ "/root/*" or
file.path like~ "/etc/ssh/*" or
file.path like~ "/etc/sudoers*"
)]EQL sequence query correlating symlink creation in LiteSpeed directories followed by access to sensitive system files by the same user on the same host within a 5-minute window, indicating potential symlink traversal exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate LiteSpeed or cPanel administrative operations that create symlinks and subsequently access config files for validation
- Configuration management tools (Ansible, Chef, Puppet) running as privileged users during deployment
- Automated backup agents that follow symlinks while traversing the filesystem
- PHP version switching tools that relink binaries and read configuration files as part of the switch
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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