Detect LiteSpeed cPanel Plugin UNIX Symbolic Link (Symlink) Following Vulnerability in Microsoft Sentinel
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
KQL Detection Query
let timeframe = 1h;
let litespeed_paths = dynamic(['/usr/local/lsws', '/opt/cpanel/ea-php', '/etc/lsws', '/var/lsws']);
let sensitive_targets = dynamic(['/etc/passwd', '/etc/shadow', '/root/', '/home/', '/etc/ssh/', '/etc/sudoers']);
union
(
DeviceFileEvents
| where TimeGenerated >= ago(timeframe)
| where ActionType in ('FileCreated', 'FileModified')
| where FolderPath has_any (litespeed_paths)
| where FileType == 'SymbolicLink'
| extend TargetPath = tostring(parse_json(AdditionalFields).SymlinkTarget)
| where TargetPath has_any (sensitive_targets)
| project TimeGenerated, DeviceName, InitiatingProcessAccountName, FolderPath, FileName, TargetPath, InitiatingProcessFileName, InitiatingProcessCommandLine, ActionType
),
(
DeviceProcessEvents
| where TimeGenerated >= ago(timeframe)
| where ProcessCommandLine matches regex @'ln\s+-s'
| where InitiatingProcessFileName in~ ('lsup.sh', 'lsphp', 'litespeed', 'lshttpd', 'cpanel-plugin')
| project TimeGenerated, DeviceName, InitiatingProcessAccountName, ProcessCommandLine, FileName, InitiatingProcessFileName, InitiatingProcessCommandLine
)
| extend AlertSeverity = 'High'
| extend Recommendation = 'Update LiteSpeed cPanel Plugin immediately. Investigate symlink targets for unauthorized file access.'
| order by TimeGenerated descDetects symbolic link creation in LiteSpeed cPanel Plugin directories pointing to sensitive system files, and symlink commands spawned by LiteSpeed processes. Covers both file event telemetry and process execution telemetry for breadth.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate LiteSpeed plugin updates that create internal symlinks during installation or upgrade
- cPanel or WHM administrative scripts performing routine maintenance that involve symlinking PHP binaries
- Hosting provider automation tools that manage multi-PHP environments using symlinks
- Security scanning tools that enumerate symlinks as part of configuration audits
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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