Detect RoundCube Webmail Cross-Site Scripting (XSS) Exploitation Attempt in CrowdStrike LogScale
Detects exploitation attempts targeting CVE-2025-68461, a stored/reflected cross-site scripting vulnerability in RoundCube Webmail. This vulnerability, listed in CISA's Known Exploited Vulnerabilities catalog, allows attackers to inject malicious scripts via email content, potentially leading to session hijacking, credential theft, or further compromise of the mail server environment. Affected versions include RoundCube Webmail prior to 1.5.12 and 1.6.12.
MITRE ATT&CK
LogScale Detection Query
#event_simpleName=NetworkConnectIP4
| NetworkRemotePort in (80, 443, 8080, 8443)
| RemoteAddressIP4 != "127.0.0.1"
// Look for RoundCube webmail process context
| join (
#event_simpleName=ProcessRollup2
| ImageFileName in ("/usr/share/roundcube/*", "*\\roundcube\\*", "*\\webmail\\*")
| CommandLine matches regex "(?i)(php|php-fpm)"
) [LocalAddressIP4, aid]
| groupby [RemoteAddressIP4, LocalAddressIP4, LocalPort, aid, ComputerName]
| stats count() as ConnectionCount by RemoteAddressIP4, LocalAddressIP4, ComputerName, LocalPort
| where ConnectionCount > 5
| sort ConnectionCount desc
// Supplemental: Script engine spawned from web process
| union (
#event_simpleName=ProcessRollup2
| ParentBaseFileName in ("php", "php-fpm", "php7.4", "php8.0", "php8.1", "php8.2", "php8.3")
| FileName in ("sh", "bash", "curl", "wget", "python", "python3", "perl", "nc", "ncat")
| CommandLine != ""
| select [ComputerName, UserName, ParentBaseFileName, FileName, CommandLine, aid, timestamp]
)CrowdStrike CQL detecting anomalous network connections and process spawning from RoundCube PHP processes, which may indicate successful XSS-to-RCE pivot or webshell activity following CVE-2025-68461 exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate PHP-based mail processing scripts executing shell commands for maintenance tasks
- RoundCube plugins that spawn helper processes for attachment handling or virus scanning
- Cron-based PHP scripts associated with the RoundCube installation running scheduled tasks
- System administrators running diagnostic commands in the context of the webmail PHP process
Other platforms for CVE-2025-68461
Testing Methodology
Validate this detection against 4 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 1RoundCube XSS - Basic Script Tag Injection via Compose
Expected signal: Web server logs will show POST request to RoundCube compose endpoint with HTML body containing `<script>` tags. PHP error logs may show sanitization failures if vulnerable version is running.
- Test 2RoundCube XSS - SVG OnLoad Event Handler Injection
Expected signal: Network logs showing POST to RoundCube with SVG onload payload. If victim opens the email in the vulnerable version, outbound HTTP GET request to `attacker.lab.local/exfil/` with base64-encoded cookie data.
- Test 3RoundCube XSS - Stored Payload via Contact/Addressbook Import
Expected signal: Web server log showing multipart POST to addressbook import endpoint. If vulnerability exists, subsequent GET requests to contact detail pages will trigger the stored XSS, generating outbound HTTP requests to `attacker.lab.local`.
- Test 4RoundCube XSS - Verify Patch Effectiveness Post-Update
Expected signal: HTTP response body should NOT contain raw `<script>` tags if the patch is applied — they should be HTML-escaped to `<script>`. Grep count of 0 confirms effective sanitization.
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