CVE-2020-5722: Grandstream UCM6200 SQLi Vulnerability

CVE-2020-5722 Overview

CVE-2020-5722 is a critical SQL injection vulnerability affecting the HTTP interface of the Grandstream UCM6200 series IP PBX systems. This unauthenticated remote vulnerability allows attackers to execute arbitrary SQL queries through specially crafted HTTP requests, ultimately enabling shell command execution as root on vulnerable firmware versions before 1.0.19.20, or HTML injection in password recovery emails on versions before 1.0.20.17.

Critical Impact

This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Unauthenticated attackers can achieve complete system compromise with root-level access on affected Grandstream UCM6200 IP PBX devices.

Affected Products

• Grandstream UCM6200 Series Firmware versions before 1.0.19.20 (Remote Code Execution)
• Grandstream UCM6200 Series Firmware versions before 1.0.20.17 (HTML Injection)
• Grandstream UCM6200 Hardware Platform

Discovery Timeline

• 2020-03-23 - CVE-2020-5722 published to NVD
• 2025-10-31 - Last updated in NVD database

Technical Details for CVE-2020-5722

Vulnerability Analysis

This SQL injection vulnerability exists in the HTTP interface of Grandstream UCM6200 series IP PBX systems. The web application fails to properly sanitize user-supplied input before incorporating it into SQL queries, creating a classic injection point that bypasses authentication entirely.

The exploitation chain is particularly severe because successful SQL injection can be escalated to arbitrary command execution with root privileges. The network-accessible attack surface combined with no authentication requirements makes this vulnerability exceptionally dangerous for exposed devices.

On firmware versions prior to 1.0.19.20, attackers can leverage the SQL injection to achieve remote code execution, executing shell commands with root privileges on the underlying operating system. For versions between 1.0.19.20 and 1.0.20.17, the vulnerability scope is reduced to HTML injection within password recovery emails, which could facilitate phishing attacks against administrators.

Root Cause

The root cause of CVE-2020-5722 is improper input validation in the HTTP interface's handling of user-supplied parameters. The vulnerable endpoint processes incoming HTTP request data and directly concatenates it into SQL query strings without proper sanitization, parameterization, or prepared statement usage.

This CWE-89 (SQL Injection) vulnerability allows attackers to break out of the intended SQL query context and inject malicious SQL statements. The web application's failure to implement secure coding practices for database interactions creates a direct path from network-accessible input to SQL query manipulation.

Attack Vector

The attack vector for CVE-2020-5722 is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by sending crafted HTTP requests to the UCM6200's web management interface.

The exploitation process involves:

1. Identifying an exposed Grandstream UCM6200 device on the network
2. Crafting malicious HTTP requests containing SQL injection payloads targeting vulnerable parameters
3. Submitting the crafted requests to the device's HTTP interface
4. Achieving SQL query manipulation that can escalate to command execution

The sendPasswordEmail functionality has been identified as one exploitation vector, where the SQL injection can be used to achieve remote code execution. Technical details and proof-of-concept exploits are available through the Packet Storm Remote Code Execution Exploit and the Tenable Security Research Advisory.

Detection Methods for CVE-2020-5722

Indicators of Compromise

• Unusual HTTP requests to the UCM6200 web interface containing SQL metacharacters such as single quotes, semicolons, or UNION SELECT statements
• Unexpected outbound network connections from UCM6200 devices to external IP addresses
• Unauthorized shell processes spawned by the web server process with root privileges
• Anomalous entries in web server access logs showing repeated requests to password recovery or authentication endpoints

Detection Strategies

• Deploy network intrusion detection rules to identify SQL injection patterns in HTTP traffic destined for UCM6200 devices
• Monitor for exploitation signatures matching known PoC payloads targeting the sendPasswordEmail function
• Implement deep packet inspection on traffic to/from IP PBX systems to detect malicious request patterns
• Establish baseline behavior for UCM6200 devices and alert on deviations such as unexpected process execution or network connections

Monitoring Recommendations

• Enable and regularly review web server access logs on UCM6200 devices for suspicious request patterns
• Monitor network traffic for connections originating from UCM6200 devices to known malicious infrastructure
• Configure SIEM alerts for authentication anomalies or password reset activity on IP PBX management interfaces
• Implement network segmentation monitoring to detect lateral movement from compromised PBX systems

How to Mitigate CVE-2020-5722

Immediate Actions Required

• Immediately update Grandstream UCM6200 firmware to version 1.0.20.17 or later to remediate all vulnerability variants
• If immediate patching is not possible, restrict network access to the UCM6200 HTTP management interface using firewall rules
• Audit UCM6200 devices for signs of compromise before and after applying patches
• Implement network segmentation to isolate IP PBX systems from general network access

Patch Information

Grandstream has released firmware updates that address this vulnerability. Organizations should upgrade to firmware version 1.0.20.17 or later to fully remediate both the remote code execution and HTML injection variants of this vulnerability.

For the latest firmware and security guidance, organizations should consult Grandstream's official support channels. Additional technical details about the vulnerability can be found in the Tenable Security Research Advisory (TRA-2020-15).

This vulnerability is tracked in the CISA Known Exploited Vulnerabilities Catalog, which mandates remediation for federal agencies and serves as guidance for all organizations.

Workarounds

• Restrict access to the UCM6200 HTTP management interface to trusted IP addresses only using network ACLs or firewall rules
• Place UCM6200 devices behind a VPN to prevent direct internet exposure of the management interface
• Disable the HTTP management interface if remote management is not required, using console or local access instead
• Implement a web application firewall (WAF) with SQL injection detection rules in front of UCM6200 devices as an additional defense layer

# Example: Firewall rule to restrict HTTP management access (iptables)
# Replace 192.168.1.0/24 with your trusted management network
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP