Detect Zimbra Collaboration Suite XSS Exploitation (CVE-2025-48700) in IBM QRadar
Detects exploitation of a stored or reflected cross-site scripting (XSS) vulnerability in Synacor Zimbra Collaboration Suite (ZCS). This KEV-listed vulnerability allows attackers to inject malicious scripts into the Zimbra web client, potentially leading to session hijacking, credential theft, or further lateral movement within the organization. XSS in webmail platforms is frequently exploited by threat actors to steal session tokens and pivot to email account compromise.
MITRE ATT&CK
QRadar Detection Query
SELECT
DATEFORMAT(devicetime, 'yyyy-MM-dd HH:mm:ss') AS event_time,
sourceip,
username,
URL,
referrerURL,
responseCode,
QIDNAME(qid) AS event_name,
logsourcename(logsourceid) AS log_source
FROM events
WHERE
LOGSOURCETYPENAME(devicetype) IN ('Apache HTTP Server', 'Microsoft IIS', 'Nginx', 'Zimbra')
AND (
URL IMATCHES '.*(/zimbra/|/service/soap|/h/|/m/).*'
OR LOGSOURCETYPENAME(devicetype) = 'Zimbra'
)
AND (
URL IMATCHES '.*(<script|javascript:|onerror=|onload=|eval\(|document\.cookie|document\.location|String\.fromCharCode|atob\().*'
OR URL IMATCHES '.*(\%3Cscript|\%6A\%61\%76\%61|<).*'
OR referrerURL IMATCHES '.*(<script|javascript:|onerror=|onload=).*'
)
AND responseCode IN (200, 301, 302, 400)
AND LOGSOURCESTARTTIME(logsourceid) > NOW() - 3600000
ORDER BY devicetime DESC
LIMIT 1000QRadar AQL query that identifies XSS payload patterns in HTTP request URLs and referrer headers targeting Zimbra web paths, covering both raw and URL-encoded XSS variants.
Data Sources
Required Tables
False Positives & Tuning
- Automated vulnerability scanners running authorized assessments against Zimbra
- Email campaign tracking URLs that contain encoded characters resembling XSS
- Custom Zimbra zimlets or integrations that pass HTML content through URL parameters
- Web application firewall logs that capture blocked XSS attempts from external sources
Other platforms for CVE-2025-48700
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 1Basic Reflected XSS Probe via Zimbra Search Parameter
Expected signal: Web server access log entry showing GET /zimbra/h/search with q=%3Cscript%3E... URL-encoded payload, HTTP 200 response, source IP of test system
- Test 2Event Handler XSS Payload Delivery via Zimbra URL Parameter
Expected signal: Web server access log showing GET requests to /zimbra/h/compose and /zimbra/h/ with onerror= and onload= patterns in URI query strings, HTTP response codes
- Test 3Simulated Session Cookie Exfiltration via XSS in Zimbra (Post-Exploitation)
Expected signal: Outbound HTTP GET request from Zimbra user's source IP to external attacker-controlled IP containing URL-encoded session token data in the query string; proxy/firewall logs showing unusual outbound connection from Zimbra webmail user IP
- Test 4Stored XSS Payload Submission via Zimbra SOAP API
Expected signal: Zimbra nginx access log showing POST to /service/soap with HTTP 200 response; Zimbra mailbox.log showing CreateContactRequest SOAP operation; POST body (if logged) containing the HTML-encoded XSS payload in the notes field
Unlock Pro Content
Get the full detection package for CVE-2025-48700 including response playbook, investigation guide, and atomic red team tests.