Detect RoundCube Webmail Cross-Site Scripting (XSS) Exploitation Attempt in Splunk
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
SPL Detection Query
index=web OR index=proxy OR index=mail
(sourcetype=access_combined OR sourcetype=apache_access OR sourcetype=nginx_access OR sourcetype=iis)
(
(uri="*/roundcube*" OR uri="*webmail*" OR uri_path="*/mail*")
AND (
uri_query IN ("*<script*", "*javascript:*", "*onerror=*", "*onload=*", "*<svg*", "*data:text/html*", "*vbscript:*")
OR uri IN ("*<script*", "*javascript:*", "*onerror=*", "*onload=*")
OR form_data IN ("*<script*", "*javascript:*", "*onerror=*", "*onload=*")
)
)
| eval xss_pattern=case(
match(uri_query, "(?i)<script"), "script_tag",
match(uri_query, "(?i)javascript:"), "javascript_uri",
match(uri_query, "(?i)on\\w+="), "event_handler",
match(uri_query, "(?i)data:text/html"), "data_uri",
true(), "generic_xss"
)
| stats count as request_count, dc(src_ip) as unique_sources, values(uri) as targeted_uris, values(xss_pattern) as attack_patterns by _time, src_ip, dest, http_method, status
| where request_count >= 1
| sort -request_countDetects XSS exploitation attempts against RoundCube Webmail endpoints by analyzing web access logs for suspicious URI patterns containing script injection payloads.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Automated web vulnerability scanners performing routine assessments
- Red team or penetration testing engagements targeting the mail infrastructure
- Legitimate encoded HTML content in query strings being misidentified as XSS
- Security research tools generating synthetic XSS payloads during testing
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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