CVE-2003-1426 in cPanel
Summary
by MITRE
Openwebmail in cPanel 5.0, when run using suid Perl, adds the directory in the SCRIPT_FILENAME environment variable to Perl s @INC include array, which allows local users to execute arbitrary code by modifying SCRIPT_FILENAME to reference a directory containing a malicious openwebmail-shared.pl executable.
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Analysis
by VulDB Data Team • 06/16/2018
The vulnerability described in CVE-2003-1426 represents a critical privilege escalation issue within the Openwebmail component of cPanel 5.0 systems. This flaw exploits a fundamental security misconfiguration in how the webmail application handles environment variables when operating with elevated privileges through suid Perl execution. The vulnerability specifically targets the SCRIPT_FILENAME environment variable which is manipulated to influence Perl's module search path. When Openwebmail processes this variable, it automatically appends the directory path to Perl's @INC array, a mechanism designed to control where Perl looks for module files. This behavior creates an exploitable condition where local attackers can manipulate the environment to inject malicious code into the execution flow.
The technical exploitation of this vulnerability relies on the fundamental principle of insecure path handling combined with privilege escalation through suid binaries. The flaw occurs because the application does not properly validate or sanitize the SCRIPT_FILENAME variable before using it to modify the Perl include path. This creates a path traversal and code injection scenario where an attacker can place a malicious openwebmail-shared.pl executable in a directory that gets loaded into @INC. The vulnerability is particularly dangerous because it leverages the suid Perl environment, which typically runs with elevated privileges, allowing arbitrary code execution with the permissions of the privileged process. This represents a classic case of insecure direct object reference combined with insecure environment variable handling, where the application trust model is violated by allowing external input to influence critical execution paths.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise when the affected cPanel installation runs with suid Perl permissions. Attackers can leverage this flaw to execute arbitrary commands with elevated privileges, potentially gaining root access to the hosting server. The vulnerability affects systems where Openwebmail is configured to run in suid mode, which is common in shared hosting environments where multiple users need access to email services. This creates a significant risk for hosting providers and their customers, as the compromise of a single user account could lead to unauthorized access to the entire server infrastructure. The exploitability is enhanced by the fact that the SCRIPT_FILENAME environment variable is typically set by web servers during HTTP request processing, making it accessible to attackers who can manipulate web request parameters to influence the vulnerable application's behavior.
Mitigation strategies for CVE-2003-1426 should focus on eliminating the suid Perl execution model where possible, as this fundamentally removes the privilege escalation vector. System administrators should ensure that Openwebmail is configured to run without suid permissions, using alternative authentication methods that don't require elevated privileges. The recommended approach involves implementing proper input validation and sanitization for environment variables, specifically ensuring that SCRIPT_FILENAME cannot be manipulated to influence the Perl include path. This vulnerability aligns with CWE-78 and CWE-20 categories, representing command injection and input validation flaws respectively. Organizations should also consider implementing the principle of least privilege by running web applications with minimal required permissions and avoiding the use of suid binaries for web applications. Additionally, regular security auditing of web application configurations and environment variable handling should be conducted to prevent similar vulnerabilities from being introduced in future deployments. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the use of vulnerable system components to gain elevated access rights.