CVE-2024-20358: Cisco ASA Software RCE Vulnerability

CVE-2024-20358 Overview

CVE-2024-20358 is a command injection vulnerability in the restore functionality of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software. The vulnerability exists because the contents of a backup file are improperly sanitized during the restore process. An authenticated, local attacker with administrator-level privileges can exploit this flaw by restoring a specially crafted backup file to an affected device, potentially executing arbitrary commands on the underlying Linux operating system with root-level privileges.

Critical Impact

Successful exploitation allows an authenticated administrator to escalate privileges and execute arbitrary commands as root on the underlying Linux operating system, potentially leading to complete device compromise.

Affected Products

• Cisco Adaptive Security Appliance (ASA) Software versions 9.8.x through 9.20.x
• Cisco Firepower Threat Defense (FTD) Software versions 6.2.3 through 7.4.1
• Various ASA hardware appliances and FTD managed devices running vulnerable software versions

Discovery Timeline

• April 24, 2024 - CVE-2024-20358 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2024-20358

Vulnerability Analysis

This command injection vulnerability (CWE-78) exists in the backup restore functionality of Cisco ASA and FTD software. The flaw arises from insufficient input validation and sanitization when processing backup file contents during a restore operation. When an administrator initiates a restore from a backup file, the system processes the archive contents without properly sanitizing embedded data that could contain malicious shell commands.

The vulnerability requires local access and administrator-level privileges to exploit, which significantly limits the attack surface. However, the impact is substantial because successful exploitation grants root-level access to the underlying Linux operating system. This allows an attacker to bypass the security controls normally enforced by the ASA/FTD management interface and directly interact with the OS layer.

An attacker who has already gained administrative access to the device (through compromised credentials or other means) could leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive configuration data, or pivot to other network resources.

Root Cause

The root cause of CVE-2024-20358 is improper input validation (CWE-78: Improper Neutralization of Special Elements used in an OS Command) in the restore functionality. The backup file restoration process fails to adequately sanitize the contents of backup archives before processing them. This allows specially crafted data within the backup file to be interpreted as shell commands by the underlying operating system, resulting in arbitrary command execution with elevated privileges.

Attack Vector

The attack requires the following conditions:

1. The attacker must have authenticated access to the Cisco ASA or FTD device with administrator-level privileges
2. The attacker must be able to create or obtain a maliciously crafted backup file
3. The attacker must initiate a restore operation using the crafted backup file on the affected device

The attack is local in nature, meaning the attacker needs direct access to the device's management interface to perform the restore operation. Once the crafted backup file is restored, the embedded malicious commands execute with root privileges on the underlying Linux operating system.

This is a post-authentication attack scenario where an insider threat or an attacker who has already compromised administrator credentials can escalate their access from the application layer to the operating system layer.

Detection Methods for CVE-2024-20358

Indicators of Compromise

• Unexpected or unauthorized backup restore operations in device logs
• Unusual processes or commands executing on the underlying Linux OS
• Modifications to system files or configurations not performed through the standard management interface
• Evidence of backup files being uploaded from untrusted or unexpected sources

Detection Strategies

• Monitor and alert on all backup restore operations, especially those initiated outside of normal change windows
• Implement file integrity monitoring on critical system directories to detect unauthorized modifications
• Review authentication logs for administrator account access patterns and anomalies
• Correlate backup restore events with subsequent suspicious process executions on the device

Monitoring Recommendations

• Enable comprehensive logging for all administrative actions including backup and restore operations
• Forward ASA/FTD logs to a centralized SIEM for correlation and anomaly detection
• Implement privileged access management (PAM) solutions to track and audit administrator activities
• Establish baseline behavior for backup operations and alert on deviations

How to Mitigate CVE-2024-20358

Immediate Actions Required

• Apply the security patches provided by Cisco as documented in the official security advisory
• Restrict administrative access to trusted personnel and implement multi-factor authentication
• Audit all administrator accounts and remove unnecessary privileged access
• Review recent backup restore activities for any suspicious operations

Patch Information

Cisco has released software updates that address this vulnerability. Organizations should upgrade to the fixed software versions as detailed in the Cisco Security Advisory. The advisory provides specific fixed release information for each affected software train and should be consulted to determine the appropriate upgrade path for your environment.

For Cisco ASA Software, ensure you are running a patched version in your deployed release train. For Cisco FTD Software, upgrade to the latest available patched release appropriate for your deployment.

Workarounds

• Implement strict access controls to limit who can perform backup and restore operations
• Only allow backup files from trusted, verified sources and implement integrity checks
• Consider network segmentation to restrict access to device management interfaces
• Implement privileged access workstations (PAWs) for administrative tasks to reduce exposure

# Example: Verify current ASA software version
show version

# Review recent backup/restore activity
show running-config | include backup
show logging | include restore

# Audit administrator accounts
show running-config | include username