CVE-2024-20738: Adobe FrameMaker Auth Bypass Flaw

CVE-2024-20738 Overview

Adobe FrameMaker Publishing Server versions 2022.1 and earlier are affected by an Improper Authentication vulnerability (CWE-287) that could result in a security feature bypass. An attacker could leverage this vulnerability to bypass authentication mechanisms and gain unauthorized access to the server. Notably, exploitation of this issue does not require user interaction, making it particularly dangerous for internet-exposed deployments.

Critical Impact

This authentication bypass vulnerability allows remote attackers to gain unauthorized access to Adobe FrameMaker Publishing Server without any user interaction, potentially compromising sensitive document publishing workflows and stored content.

Affected Products

• Adobe FrameMaker Publishing Server (all versions prior to 2022)
• Adobe FrameMaker Publishing Server 2022
• Adobe FrameMaker Publishing Server 2022 Update 1

Discovery Timeline

• 2024-02-15 - CVE-2024-20738 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-20738

Vulnerability Analysis

This vulnerability stems from improper authentication handling within Adobe FrameMaker Publishing Server. The flaw allows attackers to bypass the authentication mechanisms designed to protect the server, enabling unauthorized access without valid credentials.

FrameMaker Publishing Server is designed to automate the publishing of FrameMaker documents to various output formats. It typically handles sensitive technical documentation and integrates with enterprise content management systems. The authentication bypass allows attackers to circumvent access controls entirely, potentially gaining full administrative access to the publishing infrastructure.

The network-based attack vector means that any instance of the vulnerable software exposed to the network—whether internally or externally—is at risk. The vulnerability requires no privileges and no user interaction, making it highly exploitable in automated attack scenarios.

Root Cause

The vulnerability is classified under CWE-287 (Improper Authentication). This weakness category indicates that the software does not properly verify the identity of an actor claiming a specific identity before performing actions on their behalf. In the context of FrameMaker Publishing Server, this manifests as a failure in the authentication validation logic that allows requests to proceed without proper credential verification.

Attack Vector

The attack is network-based, meaning an attacker can remotely exploit this vulnerability without requiring local access to the target system. The attack complexity is low, requiring no special conditions or prerequisites beyond network connectivity to the vulnerable server. The attacker does not need any privileges or valid credentials to initiate the attack, and no user interaction (such as clicking a link or opening a file) is necessary for successful exploitation.

An attacker exploiting this vulnerability could:

• Gain unauthorized access to the publishing server administrative interface
• Access, modify, or delete published documents
• Potentially pivot to other systems within the network
• Disrupt document publishing workflows

Due to no verified code examples being available for this vulnerability, readers should consult the Adobe Security Advisory APSB24-10 for complete technical details regarding the authentication bypass mechanism.

Detection Methods for CVE-2024-20738

Indicators of Compromise

• Unexpected or anomalous authentication events in FrameMaker Publishing Server logs
• Access to administrative functions from unauthorized IP addresses or user accounts
• Unusual API requests or session creation without preceding valid authentication attempts
• Modified publishing configurations or document repositories without audit trails

Detection Strategies

• Monitor authentication logs for failed login attempts followed by successful access without proper credentials
• Implement network-level monitoring for connections to FrameMaker Publishing Server from unexpected sources
• Review server access logs for patterns indicating automated exploitation attempts
• Deploy intrusion detection signatures that identify authentication bypass patterns specific to this vulnerability

Monitoring Recommendations

• Enable verbose logging on FrameMaker Publishing Server to capture all authentication events
• Configure SIEM rules to alert on authentication anomalies and unauthorized administrative access
• Implement network segmentation monitoring to detect lateral movement following potential exploitation
• Regularly audit user accounts and access permissions on the publishing server

How to Mitigate CVE-2024-20738

Immediate Actions Required

• Update Adobe FrameMaker Publishing Server to the latest patched version immediately
• Restrict network access to the publishing server to only authorized IP addresses and networks
• Implement web application firewall (WAF) rules to filter potentially malicious requests
• Review access logs for evidence of past exploitation attempts
• Enable multi-factor authentication where supported as an additional security layer

Patch Information

Adobe has released a security update addressing this vulnerability. Administrators should apply the patch available through the Adobe Security Advisory APSB24-10. Organizations should prioritize this update given the critical severity and network-based attack vector.

Workarounds

• If immediate patching is not possible, restrict network access to the FrameMaker Publishing Server to trusted internal networks only
• Implement a reverse proxy with additional authentication requirements in front of the publishing server
• Temporarily disable external access to the server until the patch can be applied
• Deploy network-based access controls to limit connections to known authorized administrators

# Example: Restrict access using Windows Firewall
# Allow access only from trusted management subnet
netsh advfirewall firewall add rule name="FMPS Trusted Access" ^
    dir=in action=allow protocol=tcp localport=80,443 ^
    remoteip=10.0.1.0/24

# Block all other external access to FMPS ports
netsh advfirewall firewall add rule name="FMPS Block External" ^
    dir=in action=block protocol=tcp localport=80,443 ^
    remoteip=any