CVE-2023-38204: Adobe ColdFusion RCE Vulnerability

CVE-2023-38204 Overview

Adobe ColdFusion versions 2018u18 (and earlier), 2021u8 (and earlier), and 2023u2 (and earlier) are affected by a Deserialization of Untrusted Data vulnerability (CWE-502) that could result in arbitrary code execution. This insecure deserialization flaw allows remote attackers to execute malicious code on vulnerable ColdFusion servers without requiring any user interaction, making it particularly dangerous for internet-facing deployments.

Critical Impact

This vulnerability enables unauthenticated remote code execution on affected Adobe ColdFusion servers. Attackers can fully compromise the underlying system, steal sensitive data, deploy ransomware, or use the server as a pivot point for further network intrusion.

Affected Products

• Adobe ColdFusion 2018 Update 18 and earlier
• Adobe ColdFusion 2021 Update 8 and earlier
• Adobe ColdFusion 2023 Update 2 and earlier

Discovery Timeline

• September 14, 2023 - CVE-2023-38204 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-38204

Vulnerability Analysis

This vulnerability stems from improper handling of serialized Java objects in Adobe ColdFusion. When ColdFusion processes untrusted serialized data, it fails to adequately validate the object types being deserialized, allowing attackers to craft malicious serialized payloads that execute arbitrary code upon deserialization.

The vulnerability is particularly severe because it requires no authentication and no user interaction to exploit. An attacker with network access to a vulnerable ColdFusion instance can send specially crafted requests containing malicious serialized objects, which are then processed by the server. This attack surface is commonly exposed through web-accessible ColdFusion components and endpoints.

Deserialization vulnerabilities in Java-based applications like ColdFusion are well-documented and frequently exploited. Attackers typically leverage existing gadget chains within the application's classpath to achieve code execution through techniques that chain together legitimate method calls in unexpected ways.

Root Cause

The root cause is CWE-502: Deserialization of Untrusted Data. Adobe ColdFusion fails to properly restrict or validate the types of objects that can be deserialized from untrusted input. When the application deserializes attacker-controlled data without sufficient type checking or allowlisting, it enables the instantiation of arbitrary objects with attacker-controlled properties, ultimately leading to code execution through known Java deserialization gadget chains.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker can exploit this vulnerability by sending specially crafted HTTP requests to a vulnerable ColdFusion server. The malicious payload contains a serialized Java object that, when deserialized by the server, triggers a chain of method calls resulting in arbitrary code execution.

The exploitation flow typically involves:

1. Identifying a vulnerable ColdFusion endpoint that processes serialized data
2. Crafting a malicious serialized payload using known gadget chains (such as those from ysoserial)
3. Sending the payload to the target server via HTTP request
4. The server deserializes the payload, triggering the gadget chain and executing attacker-controlled code

Due to the nature of this vulnerability, no code example is provided. Detailed technical information can be found in the Adobe ColdFusion Security Advisory (APSB23-47).

Detection Methods for CVE-2023-38204

Indicators of Compromise

• Unexpected or anomalous HTTP POST requests to ColdFusion endpoints containing serialized Java object signatures (e.g., aced0005 hex pattern in request body)
• Unusual process spawning from ColdFusion/Java processes such as cmd.exe, powershell.exe, /bin/sh, or /bin/bash
• Unauthorized file creation or modification within ColdFusion directories or system temp folders
• Network connections from ColdFusion servers to unknown external IP addresses or command-and-control infrastructure

Detection Strategies

• Deploy web application firewall (WAF) rules to inspect and block requests containing Java serialized object magic bytes (0xAC 0xED) in request payloads
• Implement network intrusion detection signatures for known ColdFusion deserialization exploit patterns
• Monitor ColdFusion application logs for deserialization errors, exceptions, or unusual class loading activity
• Use endpoint detection and response (EDR) solutions like SentinelOne to detect suspicious child process creation from Java/ColdFusion processes

Monitoring Recommendations

• Enable verbose logging for ColdFusion and monitor for ClassNotFoundException or deserialization-related exceptions that may indicate exploitation attempts
• Implement file integrity monitoring on ColdFusion installation directories to detect unauthorized modifications
• Monitor outbound network traffic from ColdFusion servers for connections to known malicious infrastructure or unusual data exfiltration patterns
• Configure alerting for any process execution activity originating from the ColdFusion service account that falls outside normal operational patterns

How to Mitigate CVE-2023-38204

Immediate Actions Required

• Apply the security updates from Adobe immediately: ColdFusion 2018 Update 19, ColdFusion 2021 Update 9, or ColdFusion 2023 Update 3
• Restrict network access to ColdFusion administrator interfaces and limit exposure of ColdFusion endpoints to the internet
• Review and audit all ColdFusion applications for endpoints that process serialized data and consider additional input validation
• Implement network segmentation to isolate ColdFusion servers from critical internal systems

Patch Information

Adobe has released security updates to address this vulnerability in Security Bulletin APSB23-47. Organizations should update to the following versions or later:

• ColdFusion 2018: Update 19 or later
• ColdFusion 2021: Update 9 or later
• ColdFusion 2023: Update 3 or later

Workarounds

• If immediate patching is not possible, place the ColdFusion server behind a reverse proxy or WAF configured to block requests containing serialized Java objects
• Disable or restrict access to unnecessary ColdFusion components and services that may process serialized data
• Implement strict network ACLs to limit which systems can communicate with ColdFusion servers
• Consider temporarily taking vulnerable ColdFusion instances offline if they are internet-facing and cannot be patched immediately

# Example: Block Java serialized object signatures at the firewall level
# Note: Implementation varies by firewall vendor
# This example uses iptables with string matching (Linux)

# Block incoming requests containing Java serialization magic bytes
iptables -A INPUT -p tcp --dport 80 -m string --algo bm --hex-string '|aced0005|' -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --algo bm --hex-string '|aced0005|' -j DROP

# Verify ColdFusion version after patching
# Check version in ColdFusion Administrator or via:
# <cfinstall_dir>/cfusion/lib/cfusion.jar manifest