CVE-2020-13167 in Netsweeper
Summary
by MITRE
Netsweeper through 6.4.3 allows unauthenticated remote code execution because webadmin/tools/unixlogin.php (with certain Referer headers) launches a command line with client-supplied parameters, and allows injection of shell metacharacters.
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Analysis
by VulDB Data Team • 05/20/2020
The vulnerability identified as CVE-2020-13167 affects Netsweeper versions up to 6.4.3 and represents a critical remote code execution flaw that can be exploited without authentication. This vulnerability resides within the webadmin/tools/unixlogin.php component of the Netsweeper application, which processes client-supplied parameters through command line execution without proper sanitization or validation. The flaw specifically manifests when certain Referer headers are present during the request processing, creating a condition where attacker-controlled input can be directly incorporated into system commands.
The technical implementation of this vulnerability stems from improper input validation and sanitization practices within the application's web interface. When the unixlogin.php script processes incoming requests, it fails to adequately validate or escape user-supplied parameters before incorporating them into shell command executions. This creates a classic command injection vulnerability where malicious users can inject shell metacharacters such as semicolons, pipes, or other command separators that allow arbitrary command execution on the underlying operating system. The vulnerability is further exacerbated by the fact that no authentication is required to exploit this flaw, making it particularly dangerous in environments where the Netsweeper web interface is accessible to untrusted users.
From an operational perspective, this vulnerability poses severe risks to organizations utilizing Netsweeper for web content filtering and security management. Successful exploitation could allow attackers to execute arbitrary commands with the privileges of the web application user, potentially leading to complete system compromise. Attackers could leverage this vulnerability to gain unauthorized access to sensitive network resources, escalate privileges, install backdoors, or exfiltrate data from the organization's network infrastructure. The impact extends beyond immediate system compromise as the vulnerability affects the core security functionality of Netsweeper, potentially allowing attackers to bypass the very security controls the application is designed to enforce.
The vulnerability aligns with CWE-78, which specifically addresses "Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')", and can be mapped to ATT&CK technique T1059.001 for Command and Scripting Interpreter. Organizations should implement immediate mitigations including disabling or restricting access to the vulnerable unixlogin.php endpoint, implementing proper input validation and sanitization measures, and applying the vendor-provided patches as soon as they become available. Network segmentation and access controls should be strengthened to limit exposure, while monitoring should be enhanced to detect suspicious Referer headers or command execution patterns that may indicate exploitation attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within the application's codebase and ensure comprehensive protection against command injection attacks.
This vulnerability demonstrates the critical importance of proper input validation and the dangerous consequences of allowing user-supplied data to directly influence system command execution. Organizations should adopt defensive programming practices that follow the principle of least privilege and implement robust sanitization mechanisms to prevent similar issues from occurring in other applications and systems within their infrastructure.