CVE-2020-7034: Avaya Session Border Controller RCE Flaw

CVE-2020-7034 Overview

A command injection vulnerability exists in Avaya Session Border Controller for Enterprise that could allow an authenticated, remote attacker to send specially crafted messages and execute arbitrary commands with the affected system privileges. This vulnerability affects critical telecommunications infrastructure used for enterprise voice and session management.

Critical Impact

Authenticated attackers can achieve remote code execution with system-level privileges, potentially compromising enterprise VoIP infrastructure and enabling lateral movement within affected networks.

Affected Products

• Avaya Session Border Controller for Enterprise 7.x
• Avaya Session Border Controller for Enterprise 8.0
• Avaya Session Border Controller for Enterprise 8.1 through 8.1.1.x

Discovery Timeline

• 2021-04-23 - CVE CVE-2020-7034 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-7034

Vulnerability Analysis

This command injection vulnerability (CWE-78, CWE-77) allows authenticated remote attackers to inject and execute arbitrary operating system commands on affected Avaya Session Border Controller (SBC) appliances. The vulnerability exists within the message processing functionality, where user-supplied input is insufficiently sanitized before being passed to system command execution functions.

Session Border Controllers are critical network security devices that control VoIP signaling and media streams at network borders. Successful exploitation grants attackers the ability to execute commands with the privileges of the affected system process, which typically operates with elevated permissions to manage network traffic and telephony sessions.

Root Cause

The vulnerability stems from improper neutralization of special elements used in OS command construction. When processing certain messages, the SBC fails to adequately validate or sanitize input data before incorporating it into command strings that are subsequently executed by the underlying operating system. This lack of input validation allows attackers to inject shell metacharacters and additional commands that are then interpreted and executed by the system shell.

Attack Vector

The attack is network-based and requires the attacker to have valid authentication credentials to the Avaya SBC system. Once authenticated, the attacker can craft malicious messages containing command injection payloads embedded within expected input fields. These payloads leverage shell metacharacters such as semicolons, pipes, or backticks to break out of the intended command context and inject additional malicious commands.

The attacker must have network connectivity to the management or signaling interfaces of the vulnerable SBC appliance. While authentication is required, the low attack complexity combined with the high impact on confidentiality, integrity, and availability makes this a serious security concern for enterprise deployments.

Detection Methods for CVE-2020-7034

Indicators of Compromise

• Unusual command execution patterns in SBC system logs, particularly those containing shell metacharacters
• Unexpected outbound network connections from the SBC appliance to external hosts
• Creation of unauthorized user accounts or modification of system configuration files
• Anomalous process spawning from SBC application processes

Detection Strategies

• Monitor SBC application logs for malformed or suspicious message patterns containing special characters
• Implement network traffic analysis to detect command-and-control communications from SBC appliances
• Deploy file integrity monitoring on critical SBC system files and configurations
• Configure SIEM rules to alert on unusual authentication patterns followed by system-level events

Monitoring Recommendations

• Enable verbose logging on Avaya SBC appliances and forward logs to a centralized security monitoring platform
• Implement network segmentation to isolate SBC management interfaces from general network traffic
• Conduct regular reviews of authenticated sessions and administrative actions on SBC systems
• Deploy endpoint detection and response (EDR) solutions where supported to monitor for post-exploitation activity

How to Mitigate CVE-2020-7034

Immediate Actions Required

• Apply the security patches provided by Avaya as documented in the official security advisory
• Restrict network access to SBC management interfaces using firewall rules and access control lists
• Review and audit all user accounts with access to affected SBC systems
• Implement multi-factor authentication for SBC administrative access where possible
• Monitor affected systems for indicators of compromise while preparing patch deployment

Patch Information

Avaya has released security updates to address this command injection vulnerability. Organizations should consult the Avaya Security Advisory for detailed patching instructions and updated software versions. Upgrading to patched versions of Avaya Session Border Controller for Enterprise is the recommended remediation approach.

Workarounds

• Restrict authentication to trusted administrators only and minimize the number of accounts with SBC access
• Implement strict network segmentation to limit which systems can communicate with SBC management interfaces
• Deploy web application firewalls or intrusion prevention systems to filter malicious input patterns
• Enable enhanced audit logging to detect potential exploitation attempts

# Example: Restrict management interface access via firewall
# Allow management access only from trusted admin subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Enable enhanced logging for authentication events
# Consult Avaya documentation for specific logging configuration