Detect Zimbra Collaboration Suite XSS Exploitation (CVE-2025-48700) in Sumo Logic CSE
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
Sumo Detection Query
_sourceCategory=web/access OR _sourceCategory=zimbra/access
| where (%"cs-uri-stem" matches "/zimbra/*" or %"cs-uri-stem" matches "/service/soap*" or %"cs-uri-stem" matches "/h/*" or %"cs-uri-stem" matches "/m/*" or _sourceCategory matches "*zimbra*")
| where (
(%"cs-uri-query" matches "*<script*" or %"cs-uri-query" matches "*javascript:*" or %"cs-uri-query" matches "*onerror=*" or %"cs-uri-query" matches "*onload=*" or %"cs-uri-query" matches "*eval(*" or %"cs-uri-query" matches "*document.cookie*")
or (%"cs-uri-query" matches "*%3Cscript*" or %"cs-uri-query" matches "*%6A%61%76%61%73%63%72%69%70%74*")
or (%"cs-referer" matches "*<script*" or %"cs-referer" matches "*javascript:*" or %"cs-referer" matches "*onerror=*")
)
| where %"sc-status" in ("200", "301", "302", "400")
| parse field=%"cs-uri-query" "*" as payload
| timeslice 5m
| stats
count as request_count,
dcount(%"cs-uri-query") as unique_payloads,
values(%"cs-uri-query") as sample_payloads,
values(%"c-ip") as source_ips
by _timeslice, %"c-ip", %"cs-username", %"cs-host"
| where request_count >= 1
| fields - _timeslice
| sort by request_count descSumo Logic query to detect XSS injection attempts against Zimbra web interfaces by analyzing access log fields for known XSS payload patterns in query strings and referrer headers.
Data Sources
Required Tables
False Positives & Tuning
- Penetration testing tools performing automated XSS scans against Zimbra
- Legitimate HTML email content that gets URL-encoded and logged in access logs
- Third-party OAuth or SSO integrations that pass token data through Zimbra parameters
- Security awareness training platforms that demonstrate XSS via Zimbra test instances
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
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