CVE-2020-24916 in Web Server
Summary
by MITRE
CGI implementation in Yaws web server versions 1.81 to 2.0.7 is vulnerable to OS command injection.
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Analysis
by VulDB Data Team • 06/16/2024
The vulnerability identified as CVE-2020-24916 represents a critical security flaw within the Yaws web server software family, specifically affecting versions ranging from 1.81 through 2.0.7. This issue resides within the Common Gateway Interface implementation that allows web servers to execute external programs and scripts in response to client requests. The Yaws web server, known for its concurrent processing capabilities and integration with the erlang programming language, incorporates CGI functionality to extend its web application capabilities. However, this particular implementation contains a dangerous flaw that enables malicious actors to inject and execute arbitrary operating system commands on the server hosting the vulnerable software.
The technical root cause of this vulnerability stems from insufficient input validation and sanitization within the CGI processing module of Yaws. When the web server receives requests that involve CGI scripts, it fails to properly escape or filter user-supplied data before passing it to underlying operating system commands. This allows attackers to craft malicious input that gets interpreted as command-line arguments rather than data, effectively bypassing normal security boundaries. The flaw operates at the interface between web application logic and system command execution, creating a direct pathway for command injection attacks. This vulnerability aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, making it particularly dangerous for web server environments where user input is commonly processed through system calls.
The operational impact of this vulnerability is severe and far-reaching for organizations utilizing affected Yaws versions. Successful exploitation could enable attackers to execute arbitrary commands with the privileges of the web server process, potentially leading to complete system compromise. Attackers might leverage this vulnerability to escalate privileges, install backdoors, exfiltrate sensitive data, or use the compromised server as a launching point for further attacks within the network infrastructure. The vulnerability affects not only the immediate web server but could potentially allow attackers to access other systems or data stored on the same server, especially if the web server process has elevated permissions. Organizations running vulnerable versions face significant risk of data breaches, service disruption, and potential compliance violations, particularly in regulated environments where web server security is paramount.
Organizations should immediately prioritize patching their Yaws installations to versions that address this command injection vulnerability. The recommended mitigation strategy involves upgrading to Yaws versions beyond 2.0.7 where the CGI implementation has been properly secured against command injection attacks. Additionally, implementing network-level restrictions such as firewall rules to limit access to CGI endpoints can provide temporary protection while patches are deployed. Security monitoring should be enhanced to detect suspicious command execution patterns, and input validation should be strengthened at multiple layers of the application architecture. Organizations should also consider implementing web application firewalls and runtime application self-protection mechanisms to detect and prevent exploitation attempts. The vulnerability demonstrates the importance of proper input sanitization in web server implementations and reinforces the need for comprehensive security testing of all components that interface with system-level operations, particularly those that process user input through command execution pathways.