CVE-2025-11346: ILIAS RCE Vulnerability via Deserialization

CVE-2025-11346 Overview

A deserialization vulnerability has been identified in ILIAS, an open-source e-learning platform widely used in educational institutions. The vulnerability exists in the unserialize function within the Base64 Decoding Handler component. Attackers can exploit this flaw by manipulating the f_settings argument, leading to insecure deserialization that could potentially enable remote code execution on vulnerable systems.

Critical Impact

Authenticated attackers can exploit this insecure deserialization vulnerability remotely to potentially execute arbitrary code on affected ILIAS installations, compromising the confidentiality, integrity, and availability of the e-learning platform.

Affected Products

• ILIAS version 8.23 and earlier in the 8.x branch
• ILIAS version 9.13 and earlier in the 9.x branch
• ILIAS version 10.1 and earlier in the 10.x branch

Discovery Timeline

• 2025-10-06 - CVE-2025-11346 published to NVD
• 2026-01-23 - Last updated in NVD database

Technical Details for CVE-2025-11346

Vulnerability Analysis

This vulnerability is classified as an Insecure Deserialization flaw (CWE-20: Improper Input Validation). The vulnerable code path exists within the Base64 Decoding Handler component of ILIAS, specifically in the unserialize function. When processing the f_settings parameter, the application fails to properly validate or sanitize input before passing it to PHP's unserialize() function.

Insecure deserialization vulnerabilities in PHP applications are particularly dangerous because they can allow attackers to instantiate arbitrary objects and invoke magic methods (such as __wakeup() or __destruct()) that may lead to remote code execution. The attack can be launched remotely, requiring only low-level authentication to exploit.

Root Cause

The root cause of this vulnerability is the improper handling of user-controlled data in the deserialization process. The Base64 Decoding Handler accepts externally supplied data in the f_settings argument without adequate validation before passing it to the unserialize function. This allows attackers to inject malicious serialized objects that, when deserialized, can trigger unintended code execution paths through PHP object injection techniques.

Attack Vector

The vulnerability is exploitable over the network by authenticated users. An attacker must craft a malicious serialized PHP object, encode it in Base64, and submit it through the f_settings parameter. Upon processing, the ILIAS application will deserialize the malicious payload, potentially triggering a gadget chain that leads to remote code execution.

The attack flow typically involves:

1. Identifying available PHP classes within the ILIAS codebase that have exploitable magic methods
2. Crafting a serialized object payload that chains these classes together
3. Base64-encoding the payload and submitting it via the vulnerable parameter
4. The server deserializes the payload, triggering the gadget chain and executing attacker-controlled code

For detailed technical analysis of ILIAS deserialization vulnerabilities, see the SRLabs ILIAS RCE Analysis Part 2.

Detection Methods for CVE-2025-11346

Indicators of Compromise

• Unusual Base64-encoded payloads containing PHP serialized object signatures (starting with O: or a:) in request parameters
• Unexpected HTTP requests targeting the f_settings parameter with large or obfuscated payloads
• Web server logs showing requests to Base64 Decoding Handler endpoints with suspicious serialized data patterns
• Evidence of unauthorized file creation or modification on ILIAS server directories

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in HTTP requests
• Monitor application logs for deserialization errors or exceptions that may indicate exploitation attempts
• Deploy runtime application self-protection (RASP) solutions to detect and block unsafe deserialization operations
• Use SentinelOne Singularity to detect post-exploitation activities such as unauthorized process execution or file system modifications

Monitoring Recommendations

• Enable verbose logging on ILIAS application servers and forward logs to a SIEM for analysis
• Create alerts for requests containing Base64-encoded serialized PHP objects targeting known vulnerable endpoints
• Monitor for unusual PHP process spawning or outbound network connections from web server processes
• Implement file integrity monitoring on critical ILIAS directories to detect unauthorized modifications

How to Mitigate CVE-2025-11346

Immediate Actions Required

• Upgrade ILIAS to version 8.24, 9.14, or 10.2 depending on your current branch immediately
• If immediate patching is not possible, restrict access to the ILIAS platform to trusted networks only
• Review server logs for any evidence of prior exploitation attempts
• Ensure web application firewalls are configured to block known deserialization attack patterns

Patch Information

The ILIAS development team has released patched versions that address this vulnerability:

Administrators should upgrade to the corresponding fixed version for their branch as soon as possible. Review the CERT-Bund Security Advisory WID-SEC-2025-2113 for additional guidance.

Workarounds

• Implement network-level access controls to restrict ILIAS access to trusted IP ranges until patching is complete
• Deploy a Web Application Firewall with rules to block serialized PHP objects in request parameters
• Disable or restrict access to the vulnerable Base64 Decoding Handler component if not required for operations
• Consider placing ILIAS behind a reverse proxy with request inspection capabilities

# Example: Apache mod_security rule to block PHP serialized objects
SecRule ARGS "@rx [Oa]:\d+:" "id:1001,phase:2,deny,status:403,msg:'Potential PHP object injection blocked'"