CVE-2017-3066 Adobe ColdFusion Deserialization

CVE-2017-3066 is a critical security vulnerability identified in Adobe ColdFusion, a popular platform for building dynamic web applications. This vulnerability stems from improper handling of Java object deserialization within the Apache BlazeDS library, which ColdFusion utilizes for processing Action Message Format (AMF) data. Exploiting this flaw allows remote attackers to execute arbitrary code on the affected server without authentication, posing significant security risks.

What is Vulnerable to CVE-2017-3066?

The following versions of Adobe ColdFusion are susceptible to this vulnerability:

• ColdFusion 2016: Update 3 and earlier
• ColdFusion 11: Update 11 and earlier
• ColdFusion 10: Update 22 and earlier

The root cause lies in the deserialization process of untrusted Java objects within the Apache BlazeDS library. Attackers can exploit this by sending maliciously crafted AMF messages to endpoints like /flex2gateway/amf, leading to arbitrary code execution on the server. Notably, this attack does not require prior authentication, making publicly accessible ColdFusion servers particularly vulnerable.

Mitigation and Remediation for CVE-2017-3066

To protect systems from this critical vulnerability, Adobe has released security hotfixes. Users and administrators should take the following actions:

1. Apply Security Hotfixes:

   • ColdFusion (2016 release): Update to Update 4 or later.
   • ColdFusion 11: Update to Update 12 or later.
   • ColdFusion 10: Update to Update 23 or later.

2. Restrict Access to AMF Endpoints:

   • Use firewall rules to limit access to /flex2gateway/* endpoints, allowing only trusted networks.

3. Disable Unused Services:

   • If AMF services are not in use, disable them to reduce the attack surface.

4. Implement Input Validation:

   • Ensure that all deserialized data is validated to prevent malicious input from being processed.

5. Monitor and Log Activity:

   • Regularly monitor server logs for unusual activities, such as unexpected requests to AMF endpoints.

For detailed instructions and best practices, refer to Adobe’s security bulletin.

Impact of Successful Exploitation of CVE-2017-3066

Exploiting this vulnerability allows attackers to execute arbitrary code on the affected server, leading to:

• Complete System Compromise: Attackers gain full control over the server, enabling them to manipulate data, install malicious software, or use the server as a launchpad for further attacks.
• Data Breaches: Unauthorized access to sensitive information stored on the server, including personal data, intellectual property, and financial records.
• Service Disruption: Attackers can disrupt services, causing downtime, loss of revenue, and damage to reputation.

Given the severity, it is imperative to address this vulnerability promptly to safeguard organizational assets.

Proof of Concept for CVE-2017-3066

Security researchers have demonstrated exploits for this vulnerability. One such proof of concept involves sending a malicious AMF request to the vulnerable endpoint, leading to remote code execution. While full exploit details are withheld to prevent misuse, the general approach includes:

1. Crafting Malicious AMF Payloads: Utilizing tools like ColdFusionPwn to generate payloads that exploit the deserialization flaw.
2. Sending Payloads to Targeted Endpoints: Dispatching these payloads to endpoints such as http://target-server:8500/flex2gateway/amf.
3. Achieving Code Execution: Upon successful exploitation, the payload executes arbitrary commands on the server.

For testing and educational purposes, a detailed walkthrough is available in this GitHub repository.

CVE-2017-3066 represents a critical security flaw in Adobe ColdFusion’s handling of Java object deserialization. Immediate action is required to apply the necessary patches and implement recommended security measures. By doing so, organizations can protect their systems from potential exploitation and maintain the integrity of their data and services.