CVE-2020-37153: ASTPP 4.0.1 RCE Vulnerability

CVE-2020-37153 Overview

CVE-2020-37153 affects ASTPP 4.0.1, a VoIP billing solution, where multiple vulnerabilities including cross-site scripting (XSS) and command injection exist in the SIP device configuration and plugin management interfaces. Attackers can exploit these flaws to inject system commands, hijack administrator sessions, and potentially execute arbitrary code with root permissions through cron task manipulation.

Critical Impact

Successful exploitation could allow attackers to achieve remote code execution with elevated privileges, compromise administrator sessions, and gain persistent access to the underlying system through cron job manipulation.

Affected Products

• ASTPP 4.0.1
• ASTPP VoIP Billing Platform (version 4.0.1 and potentially earlier versions)

Discovery Timeline

• 2026-02-11 - CVE CVE-2020-37153 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2020-37153

Vulnerability Analysis

This vulnerability combines multiple attack vectors that create a severe security risk for ASTPP deployments. The cross-site scripting (CWE-79) component allows attackers to inject malicious scripts into web pages viewed by administrators, while the command injection vulnerability enables direct execution of system commands on the underlying server.

The attack chain typically begins with XSS exploitation to hijack an administrator session or trick them into executing malicious actions. Once administrative access is obtained, the command injection vulnerability in the SIP device configuration and plugin management interfaces can be leveraged to execute arbitrary system commands. The most dangerous aspect of this vulnerability is the ability to manipulate cron tasks, which could grant persistent root-level access to the compromised system.

Root Cause

The root cause stems from improper input validation and insufficient output encoding in the ASTPP web application. User-supplied input in the SIP device configuration and plugin management interfaces is not properly sanitized before being reflected in web pages or passed to system shell commands. This lack of input validation allows malicious payloads to be processed by the application, leading to both XSS and command injection attacks.

Attack Vector

The attack is network-based and requires user interaction, making it a targeted attack scenario. An attacker would typically:

1. Craft a malicious URL or form submission containing XSS payloads targeting the SIP device configuration or plugin management interfaces
2. Social engineer an administrator into clicking the malicious link or visiting a compromised page
3. Once the XSS payload executes in the administrator's browser context, steal session tokens or perform actions on behalf of the victim
4. Leverage the command injection vulnerability by inserting shell metacharacters into configuration fields that are processed by backend system commands
5. Establish persistent access by creating malicious cron jobs that execute with root privileges

The vulnerability requires network access to the ASTPP web interface and user interaction for the XSS component, but once an authenticated session is compromised, the command injection can be exploited directly.

Detection Methods for CVE-2020-37153

Indicators of Compromise

• Unusual HTTP requests to SIP device configuration or plugin management endpoints containing shell metacharacters (;, |, &&, backticks)
• Suspicious cron job entries that were not created by legitimate administrators
• Web server logs showing reflected XSS payloads with <script> tags or event handlers in URL parameters
• Unexpected outbound network connections from the ASTPP server to unknown external hosts

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block XSS payloads and shell command injection attempts
• Monitor system cron files (/etc/crontab, /var/spool/cron/) for unauthorized modifications
• Enable detailed logging for the ASTPP application and review for suspicious configuration changes
• Deploy endpoint detection and response (EDR) solutions to identify anomalous process execution patterns

Monitoring Recommendations

• Configure alerts for authentication events and session activity from unusual IP addresses or at unusual times
• Implement file integrity monitoring (FIM) on critical system files including cron directories and ASTPP configuration files
• Monitor for spawned shell processes (/bin/sh, /bin/bash) from the web server process
• Review web application logs for error messages that may indicate exploitation attempts

How to Mitigate CVE-2020-37153

Immediate Actions Required

• Restrict network access to the ASTPP administrative interface to trusted IP addresses only
• Implement Content Security Policy (CSP) headers to mitigate XSS exploitation
• Review and audit all cron jobs on affected systems for unauthorized entries
• Enable multi-factor authentication for administrative access if available
• Consider temporarily disabling the SIP device configuration and plugin management features until patches are applied

Patch Information

Administrators should consult the official ASTPP project on GitHub for the latest security updates and patches. Additional technical details about this vulnerability can be found in the VulnCheck ASTPP Advisory and Exploit-DB #47889.

Workarounds

• Place the ASTPP administrative interface behind a VPN or reverse proxy with strong authentication
• Implement input validation at the web server level using ModSecurity or similar WAF solutions
• Remove or disable the affected plugin management functionality if not required for operations
• Apply the principle of least privilege by ensuring the web application runs with minimal system permissions
• Regularly audit and rotate administrative credentials