CVE-2024-30164: AWS Client VPN Buffer Overflow Vulnerability

CVE-2024-30164 Overview

CVE-2024-30164 is a buffer overflow vulnerability affecting the Amazon AWS Client VPN application across Windows, macOS, and Linux platforms. This memory corruption flaw could potentially allow a local actor with existing access to execute arbitrary commands with elevated permissions, representing a significant privilege escalation risk in enterprise environments utilizing AWS VPN infrastructure.

Critical Impact

Local attackers with high privileges can exploit this buffer overflow to execute arbitrary commands with elevated permissions, potentially compromising the entire system and gaining unauthorized access to sensitive resources connected through the VPN.

Affected Products

• Amazon AWS Client VPN for Windows (versions prior to 3.11.1)
• Amazon AWS Client VPN for macOS (versions prior to 3.9.1)
• Amazon AWS Client VPN for Linux (versions prior to 3.12.1)

Discovery Timeline

• 2024-05-28 - CVE-2024-30164 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-30164

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw exists within the AWS Client VPN application's handling of data buffers, where insufficient bounds checking allows data to be written beyond allocated memory boundaries.

Buffer overflows of this nature occur when an application copies data into a fixed-size buffer without properly validating that the input size does not exceed the buffer's capacity. When exploited, the attacker can overwrite adjacent memory locations, potentially including return addresses, function pointers, or other critical data structures that control program execution flow.

The local attack vector requires the attacker to have existing access to the target system. However, the ability to execute arbitrary commands with elevated permissions means that a compromised low-privilege account or malicious insider could leverage this vulnerability to escalate to administrative or root-level access.

Root Cause

The root cause of CVE-2024-30164 is improper input validation during buffer copy operations within the AWS Client VPN application. The vulnerable code path fails to verify that incoming data fits within the allocated buffer space before performing memory copy operations.

This type of vulnerability typically arises when using unsafe memory manipulation functions (such as strcpy, sprintf, or memcpy) without proper length validation. The AWS Client VPN application across all three platforms (Windows, macOS, and Linux) contained similar vulnerable code patterns, requiring platform-specific patches to remediate the issue.

Attack Vector

The attack requires local access to the target system with high privileges. An attacker would need to craft specially formatted input data designed to overflow the vulnerable buffer. Upon successful exploitation, the attacker can:

1. Overwrite critical memory structures to gain control of program execution
2. Execute arbitrary commands with the elevated permissions of the VPN client process
3. Potentially persist access through modification of system configurations
4. Access or exfiltrate data from VPN-connected resources

It is worth noting that while this vulnerability shares the same macOS patch version (3.9.1) with CVE-2024-30165, they are distinct vulnerabilities with different root causes and exploitation paths.

Detection Methods for CVE-2024-30164

Indicators of Compromise

• Unusual process behavior or crashes originating from the AWS Client VPN application
• Unexpected child processes spawned by the VPN client with elevated privileges
• Memory access violations or application exceptions logged in system event logs
• Anomalous system calls or API invocations from the VPN client process

Detection Strategies

• Monitor for abnormal memory consumption patterns in the AWS Client VPN process
• Implement endpoint detection rules to identify buffer overflow exploitation attempts targeting VPN applications
• Deploy application whitelisting to detect unauthorized code execution from VPN client directories
• Configure SentinelOne Singularity to monitor for privilege escalation attempts associated with VPN software

Monitoring Recommendations

• Enable verbose logging for the AWS Client VPN application to capture potential exploitation attempts
• Configure security monitoring tools to alert on unexpected privilege changes following VPN client activity
• Implement file integrity monitoring on VPN client installation directories
• Review system logs regularly for VPN-related application crashes or errors that may indicate exploitation attempts

How to Mitigate CVE-2024-30164

Immediate Actions Required

• Update AWS Client VPN for Windows to version 3.11.1 or later immediately
• Update AWS Client VPN for macOS to version 3.9.1 or later immediately
• Update AWS Client VPN for Linux to version 3.12.1 or later immediately
• Audit all systems with AWS Client VPN installed to identify vulnerable versions

Patch Information

Amazon has released patched versions of the AWS Client VPN application for all affected platforms. Organizations should prioritize updating to the following minimum versions:

Workarounds

• Restrict local system access to trusted users only to reduce the attack surface
• Implement application control policies to limit which processes can interact with the VPN client
• Deploy host-based intrusion prevention systems to detect and block exploitation attempts
• Consider network segmentation to limit the impact of a compromised VPN client endpoint

Organizations should apply the official patches as soon as possible, as workarounds only reduce risk and do not fully remediate the vulnerability. For enterprise deployments, consider using managed software distribution tools to ensure consistent patching across all endpoints.