CVE-2024-20295: Cisco IMC Privilege Escalation Flaw

CVE-2024-20295 Overview

A command injection vulnerability exists in the Command Line Interface (CLI) of Cisco Integrated Management Controller (IMC) that could allow an authenticated, local attacker to execute arbitrary commands on the underlying operating system and escalate privileges to root. This vulnerability arises from insufficient validation of user-supplied input in CLI commands.

To successfully exploit this vulnerability, an attacker must have read-only or higher privileges on an affected device. By submitting specially crafted CLI commands, an attacker can bypass input validation controls and inject malicious commands that execute with elevated privileges.

Critical Impact

Authenticated attackers with minimal privileges can achieve full root access on affected Cisco IMC devices, potentially compromising server management infrastructure and gaining persistent access to critical systems.

Affected Products

• Cisco Integrated Management Controller (IMC)
• Cisco UCS C-Series Rack Servers
• Cisco UCS S-Series Storage Servers

Discovery Timeline

• April 24, 2024 - CVE-2024-20295 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2024-20295

Vulnerability Analysis

This vulnerability is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The Cisco IMC CLI fails to properly sanitize user-supplied input before incorporating it into operating system commands executed on the underlying host.

The attack requires local access and at least read-only privileges on the affected device, meaning the attacker must first authenticate to the IMC interface. However, once authenticated with even minimal privileges, the insufficient input validation allows the attacker to inject shell metacharacters or command separators that break out of the intended command context and execute arbitrary commands with root privileges.

Root Cause

The root cause of this vulnerability is insufficient validation of user-supplied input within the Cisco IMC CLI command processing logic. When users submit commands through the CLI interface, the input is passed to underlying operating system functions without adequate sanitization or filtering of dangerous characters such as semicolons, pipes, backticks, or command substitution syntax.

This allows specially crafted input containing shell metacharacters to be interpreted as additional commands rather than data, enabling command injection. The underlying service appears to run with elevated privileges, allowing injected commands to execute as root.

Attack Vector

This vulnerability requires local access to the affected device's CLI interface. The attack vector can be described as follows:

1. Initial Access: Attacker authenticates to the Cisco IMC CLI using valid credentials with read-only or higher privileges
2. Input Injection: Attacker submits a crafted CLI command containing shell metacharacters or command separators
3. Command Execution: The vulnerable CLI component fails to sanitize the input and passes it to the underlying OS shell
4. Privilege Escalation: Injected commands execute with root privileges, granting the attacker full control

The vulnerability mechanism involves improper handling of user input in CLI command parameters. When special shell characters are included in command arguments, they are not properly escaped or filtered, allowing an attacker to append or inject additional shell commands that execute in the context of the underlying operating system with root privileges. For detailed technical information, refer to the Cisco Security Advisory.

Detection Methods for CVE-2024-20295

Indicators of Compromise

• Unexpected processes spawned from IMC CLI service processes
• Unusual command execution patterns in system logs with root privileges
• Authentication events followed by privilege escalation indicators
• Presence of unauthorized user accounts or SSH keys on the IMC system

Detection Strategies

• Monitor IMC CLI audit logs for commands containing shell metacharacters such as ;, |, &&, backticks, or $() syntax
• Implement behavioral analysis to detect anomalous command patterns from authenticated users
• Deploy endpoint detection and response (EDR) solutions to monitor for unexpected process trees originating from IMC services
• Configure alerting for any privilege changes or new root-level access on IMC devices

Monitoring Recommendations

• Enable verbose logging on all Cisco IMC devices and forward logs to a centralized SIEM
• Implement user behavior analytics to baseline normal CLI usage patterns
• Monitor for process execution anomalies on IMC hosts, particularly commands executed as root
• Review authentication logs for suspicious login patterns or brute-force attempts targeting IMC interfaces

How to Mitigate CVE-2024-20295

Immediate Actions Required

• Apply the latest security patches from Cisco as soon as they become available
• Restrict CLI access to only essential personnel with legitimate administrative needs
• Implement network segmentation to limit access to IMC management interfaces
• Review and audit all accounts with access to IMC CLI, removing unnecessary privileges
• Enable multi-factor authentication for IMC access where supported

Patch Information

Cisco has released security updates to address this vulnerability. Administrators should consult the Cisco Security Advisory for specific patch versions and upgrade instructions applicable to their deployment. Organizations should prioritize patching based on the exposure of their IMC infrastructure and follow Cisco's recommended upgrade path for their specific product versions.

Workarounds

• Restrict network access to IMC management interfaces using firewall rules and ACLs
• Limit CLI access to only trusted administrators through role-based access controls
• Place IMC management interfaces on isolated management networks not accessible from general user segments
• Monitor and audit all CLI sessions for suspicious activity until patches can be applied

# Example: Restrict IMC access via firewall rules
# Only allow management access from trusted admin network
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
iptables -A INPUT -p tcp --dport 22 -j DROP