Detect Synacor Zimbra Collaboration Suite PHP Remote File Inclusion (CVE-2025-68645) in Sumo Logic CSE
Detects exploitation of CVE-2025-68645, a PHP Remote File Inclusion (RFI) vulnerability in Synacor Zimbra Collaboration Suite (ZCS). CWE-98 class vulnerabilities allow attackers to inject and execute remote PHP files via unsanitized user-controlled input passed to PHP file inclusion functions, enabling arbitrary code execution in the context of the web server process. This vulnerability is listed in the CISA Known Exploited Vulnerabilities catalog.
MITRE ATT&CK
- Tactic
- Initial Access Execution Persistence
Sumo Detection Query
_sourceCategory=zimbra OR _sourceCategory=webserver/zimbra OR _sourceHost=*zimbra*
| parse regex field=_raw "(?P<src_ip>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}).*?\"(?P<method>GET|POST|PUT)\s(?P<uri_path>[^\s]+)\s" nodrop
| parse regex field=_raw "(?P<param_kv>[a-zA-Z_0-9]+=(https?://|ftp://|file://|php://input)[^\s&\"]+)" nodrop
| parse regex field=_raw "(?P<rfi_cmd>(?:include|require|include_once|require_once)\s*\(\s*[\$'\"]*https?://)" nodrop
| parse regex field=_raw "(?P<suspicious_file>/opt/zimbra/(?:data/tmp|store|index)/[^\s]+\.php)" nodrop
| where !isEmpty(param_kv) OR !isEmpty(rfi_cmd) OR !isEmpty(suspicious_file)
| count by _sourceHost, src_ip, uri_path, param_kv, rfi_cmd, suspicious_file
| sort by _count descSumo Logic query detecting Zimbra ZCS PHP RFI exploitation through URL parameter injection patterns, PHP include/require with remote URLs, and unexpected PHP file creation in Zimbra data directories.
Data Sources
Required Tables
False Positives & Tuning
- Zimbra administrator actions in the admin console that use URL-formatted configuration values
- Third-party Zimbra monitoring tools polling ZCS endpoints with complex query strings
- Zimbra backup solutions that reference remote storage URLs in configuration parameters
- Load balancer health checks generating non-standard HTTP request patterns
Other platforms for CVE-2025-68645
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 1Simulate PHP RFI via HTTP Request Parameter Injection
Expected signal: Web server access log entry with URL parameter containing http://attacker.lab/malicious.php; network connection attempt from PHP process to attacker.lab:80
- Test 2Create Simulated Web Shell in Zimbra Data Directory
Expected signal: File creation event for /opt/zimbra/data/tmp/lab_test/shell_test_atomic.php; auditd syscall event for open/write by test user
- Test 3PHP Process Invoking Remote File Fetch (RFI Simulation)
Expected signal: Process telemetry showing php binary with command-line containing http:// URL; network connection attempt from php process to 127.0.0.1:9999 (or external IP in real attack)
- Test 4Zimbra Config File Access by Non-Zimbra Process (Post-Exploitation Credential Harvest)
Expected signal: Auditd open/read syscall event on /opt/zimbra/conf/localconfig.xml by non-zimbra UID; file access timestamp update visible in stat output
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Get the full detection package for CVE-2025-68645 including response playbook, investigation guide, and atomic red team tests.