A critical security flaw, identified as CVE-2025-53772, has been uncovered in Microsoft’s Internet Information Services (IIS) Web Deploy tool. This vulnerability allows authenticated attackers to execute arbitrary code on target servers, posing significant risks to organizations utilizing this deployment tool.
Understanding CVE-2025-53772
The vulnerability resides in the deserialization process of HTTP headers within the msdeployagentservice and msdeploy.axd endpoints of IIS Web Deploy. Specifically, the flaw involves the processing of a Base64-encoded, GZip-compressed payload extracted from the MSDeploy.SyncOptions HTTP header. The sequence of Base64 decoding, GZip decompression, and subsequent deserialization using BinaryFormatter.Deserialize() lacks proper input validation. This oversight permits malicious payloads to instantiate dangerous objects, leading to remote code execution.
Proof-of-Concept Exploit
A publicly available proof-of-concept (PoC) exploit demonstrates how attackers can leverage this vulnerability. By crafting a specific payload and sending it via an HTTP POST request to the /msdeploy.axd endpoint, an attacker can trigger the execution of arbitrary commands on the server. For instance, the PoC showcases the launching of the calculator application (calc.exe) on the affected server, illustrating the potential for more malicious activities.
Risk Assessment
The severity of CVE-2025-53772 is underscored by its Common Vulnerability Scoring System (CVSS) score of 8.8, categorizing it as a high-risk vulnerability. The risk factors include:
– Affected Products: Microsoft Web Deploy, specifically the msdeployagentservice and msdeploy.axd components.
– Impact: Remote Code Execution (RCE), allowing attackers to run arbitrary code on the server.
– Exploit Prerequisites: The attacker must have authenticated access to the Web Deploy service, network access to the deployment endpoint, and the capability to send crafted HTTP headers.
Mitigation Strategies
To protect systems from potential exploitation, organizations should implement the following mitigation measures:
1. Disable the Web Deploy Agent Service (MsDepSvc): Temporarily disabling this service can prevent exploitation until a permanent fix is applied.
2. Enforce Strict Network Access Control Lists (ACLs): Restrict access to the msdeploy.axd endpoint to trusted sources only, minimizing the attack surface.
3. Apply Inbound Filtering: Configure network devices to block unexpected MSDeploy.SyncOptions headers, reducing the risk of malicious payloads reaching the server.
4. Update to Secure Serialization Methods: Replace the use of BinaryFormatter with more secure serializers, such as DataContractSerializer, which enforce explicit type contracts and enhance input validation.
Long-Term Remediation
Beyond immediate mitigation, organizations should focus on long-term remediation strategies:
– Code Review and Refactoring: Conduct thorough code reviews to identify and rectify unsafe deserialization practices. Refactoring code to use secure serialization methods can prevent similar vulnerabilities in the future.
– Regular Security Audits: Implement regular security audits and penetration testing to identify and address potential vulnerabilities proactively.
– Employee Training: Educate developers and system administrators on secure coding practices and the importance of input validation to prevent deserialization vulnerabilities.
Conclusion
The discovery of CVE-2025-53772 highlights the critical need for robust security practices in software development and deployment. Organizations utilizing Microsoft’s IIS Web Deploy must prioritize applying the recommended mitigations and updates to safeguard their systems against potential exploitation. Continuous vigilance and adherence to secure coding standards are essential in mitigating the risks associated with such vulnerabilities.
