CVE-2022-20655 Overview
A command injection vulnerability exists in the implementation of the CLI on devices running ConfD that could allow an authenticated, local attacker to execute arbitrary commands on the underlying operating system. The vulnerability stems from insufficient validation of process arguments, enabling attackers to inject malicious commands during process execution with the privilege level of ConfD, which is commonly root.
Critical Impact
Successful exploitation allows attackers to execute arbitrary commands with root-level privileges on affected devices, potentially leading to complete system compromise.
Affected Products
- Cisco devices running ConfD CLI implementations
- Network devices utilizing ConfD management framework
- Systems with vulnerable CLI argument processing
Discovery Timeline
- 2024-11-15 - CVE-2022-20655 published to NVD
- 2024-11-18 - Last updated in NVD database
Technical Details for CVE-2022-20655
Vulnerability Analysis
This vulnerability is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The flaw exists in the CLI implementation of ConfD, a network configuration management framework widely used in network equipment.
The vulnerability requires local access and authentication, meaning an attacker must first gain legitimate access to the device before exploitation. However, once authenticated, the attacker can leverage the command injection flaw to escalate their privileges and execute arbitrary system commands.
The impact is significant because ConfD typically runs with elevated privileges (commonly root) to perform its network configuration management duties. When command injection succeeds, the injected commands inherit these elevated privileges, allowing attackers to compromise the entire system.
Root Cause
The root cause of this vulnerability is insufficient validation and sanitization of process arguments within the ConfD CLI implementation. When user-supplied input is passed to system processes without proper escaping or validation, malicious characters and command sequences can be interpreted as executable commands rather than data.
The vulnerable code path fails to properly neutralize special elements (such as shell metacharacters) before incorporating user input into OS commands. This allows attackers to break out of the intended command context and inject their own commands.
Attack Vector
The attack requires local access to the device with valid authentication credentials. An attacker with legitimate CLI access can craft specially formed input containing shell metacharacters or command sequences. When this input is processed by the vulnerable CLI implementation, the injected commands are executed with the same privilege level as the ConfD process.
Common command injection techniques that may apply include:
- Using semicolons (;) to chain commands
- Using pipe operators (|) to redirect output
- Using backticks or $() for command substitution
- Leveraging newline characters to separate commands
The attacker's injected commands execute with ConfD's privilege level, which is typically root, granting complete control over the affected system.
Detection Methods for CVE-2022-20655
Indicators of Compromise
- Unexpected processes spawned as child processes of ConfD or related CLI services
- Unusual command execution patterns in system logs originating from ConfD processes
- Authentication logs showing repeated failed attempts followed by successful logins
- New user accounts or SSH keys created without administrative intent
- Modifications to system files or configurations outside normal ConfD operations
Detection Strategies
- Monitor system call activity from ConfD processes for unexpected shell invocations or command executions
- Implement behavioral analysis to detect anomalous CLI command patterns that deviate from normal administrative activity
- Configure audit logging for all CLI sessions and review for suspicious command sequences containing shell metacharacters
- Deploy endpoint detection solutions capable of identifying command injection attack patterns
Monitoring Recommendations
- Enable comprehensive logging for all ConfD CLI sessions and correlate with system-level process monitoring
- Implement real-time alerting for processes spawned by ConfD that match suspicious patterns such as reverse shells or reconnaissance tools
- Review authentication logs regularly for accounts accessing CLI interfaces from unexpected sources
- Monitor file integrity on critical system files that could be modified following successful exploitation
How to Mitigate CVE-2022-20655
Immediate Actions Required
- Review the Cisco Security Advisory for Command Injection and the Cisco Security Advisory for CLI Vulnerability for specific patch information
- Apply vendor-supplied security patches as soon as they are available for your specific product version
- Audit and restrict local access to affected devices, ensuring only authorized personnel have CLI access
- Implement the principle of least privilege for all user accounts with CLI access
Patch Information
Cisco has released security advisories addressing this vulnerability. Administrators should consult the official Cisco Security Advisories for detailed patch and upgrade information specific to their deployed products. The relevant advisories are available at the Cisco Security Center and provide product-specific remediation guidance.
Workarounds
- Restrict CLI access to only essential administrative personnel and enforce strong authentication mechanisms
- Implement network segmentation to limit access to management interfaces from trusted networks only
- Enable enhanced logging and monitoring on affected devices to detect exploitation attempts
- Consider disabling non-essential CLI features if they are not required for operations
# Example: Restrict CLI access via access control lists
# Configure management access restrictions on Cisco devices
# Note: Specific configuration varies by platform - consult Cisco documentation
# Limit management access to trusted networks
ip access-list standard MGMT-ACCESS
permit 10.0.0.0 0.0.0.255
deny any log
# Apply to management interface/VTY lines
line vty 0 15
access-class MGMT-ACCESS in
transport input ssh
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
