CVE-2024-5290: Wpa Supplicant Privilege Escalation Flaw

CVE-2024-5290 Overview

CVE-2024-5290 is a local privilege escalation vulnerability affecting Ubuntu's wpa_supplicant package. The vulnerability allows a local unprivileged attacker to load arbitrary shared objects, potentially escalating privileges to the user that wpa_supplicant runs as—which is typically root. This is classified as a Controlled Search Path Element vulnerability (CWE-427).

The attack surface includes users with membership in the netdev group or access to the D-Bus interface of wpa_supplicant. These access vectors allow an unprivileged user to specify an arbitrary path to a module that will be loaded by the wpa_supplicant process. Additional escalation paths may also exist beyond these documented vectors.

Critical Impact

Local attackers can achieve root-level privilege escalation through arbitrary shared object loading in wpa_supplicant, compromising system integrity.

Affected Products

• w1.fi wpa_supplicant
• Canonical Ubuntu Linux

Discovery Timeline

• August 7, 2024 - CVE-2024-5290 published to NVD
• September 17, 2024 - Last updated in NVD database

Technical Details for CVE-2024-5290

Vulnerability Analysis

The vulnerability exists in Ubuntu's wpa_supplicant implementation, specifically in how the application handles module loading paths. wpa_supplicant is a critical networking service that typically runs with elevated (root) privileges to manage wireless network connections.

The flaw allows attackers who have either netdev group membership or D-Bus interface access to inject a malicious path pointing to an attacker-controlled shared object (.so file). When wpa_supplicant loads this module, it executes with the service's privileges—commonly root—resulting in complete system compromise.

This vulnerability is particularly concerning in multi-user environments where non-administrative users may have netdev group membership for legitimate networking tasks, or in scenarios where the D-Bus interface is accessible to unprivileged processes.

Root Cause

The root cause is a Controlled Search Path Element weakness (CWE-427). The wpa_supplicant implementation fails to properly validate or restrict the paths from which shared objects can be loaded. This allows users with specific group memberships or interface access to specify arbitrary file system paths, leading to the loading of malicious code.

The insufficient input validation on module paths creates a trust boundary violation where user-controlled input directly influences privileged code execution.

Attack Vector

The attack requires local access to the system and can be executed through two primary vectors:

1. netdev Group Membership: Users in the netdev group can configure wpa_supplicant to load modules from arbitrary paths. This group is commonly assigned to users who need to manage network connections.

2. D-Bus Interface Access: The wpa_supplicant D-Bus interface can be leveraged to specify malicious module paths. D-Bus access control policies may inadvertently grant this capability to unprivileged processes.

An attacker would craft a malicious shared object containing code to be executed with root privileges, place it in an accessible location, and then trigger wpa_supplicant to load it through either vector.

For detailed technical analysis and exploitation methodology, see the Snyk Blog on Privilege Escalation and the Launchpad Bug Report.

Detection Methods for CVE-2024-5290

Indicators of Compromise

• Unexpected shared object files (.so) appearing in non-standard directories
• Unusual wpa_supplicant process behavior or unexpected child processes
• D-Bus messages targeting wpa_supplicant from unexpected sources
• Modified wpa_supplicant configuration files referencing unusual module paths
• New processes spawned with root privileges originating from wpa_supplicant

Detection Strategies

• Monitor wpa_supplicant configuration changes for unusual module path specifications
• Audit D-Bus traffic to wpa_supplicant for method calls that specify external module paths
• Track file system changes in directories where malicious .so files might be staged
• Monitor for privilege escalation patterns originating from users in the netdev group

Monitoring Recommendations

• Implement file integrity monitoring on wpa_supplicant configuration directories
• Configure audit rules to log D-Bus interactions with the wpa_supplicant service
• Monitor for new shared object creation in user-writable directories
• Alert on unexpected wpa_supplicant module loading events in system logs

How to Mitigate CVE-2024-5290

Immediate Actions Required

• Apply the Ubuntu security update immediately via sudo apt update && sudo apt upgrade
• Review and restrict netdev group membership to only essential users
• Audit D-Bus access control policies for wpa_supplicant interfaces
• Monitor systems for signs of exploitation until patches are applied

Patch Information

Canonical has released security updates to address this vulnerability. The fix is documented in Ubuntu Security Notice USN-6945-1. Administrators should update the wpa_supplicant package through the standard Ubuntu package management system.

The patch restricts the paths from which wpa_supplicant can load modules, preventing arbitrary shared object loading from user-controlled locations.

Workarounds

• Remove unnecessary users from the netdev group to reduce attack surface
• Restrict D-Bus access to wpa_supplicant using AppArmor or D-Bus policy configurations
• Implement mandatory access control (MAC) policies to limit wpa_supplicant's file access
• Consider isolating wpa_supplicant in a container or namespace if possible

# Review current netdev group membership
getent group netdev

# Remove unnecessary users from netdev group (replace USERNAME)
sudo gpasswd -d USERNAME netdev

# Apply security updates
sudo apt update && sudo apt upgrade wpa