CVE-2017-5613 in cgiemail
Summary
by MITRE
Format string vulnerability in cgiemail and cgiecho allows remote attackers to execute arbitrary code via format string specifiers in a template file.
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Analysis
by VulDB Data Team • 07/06/2024
The vulnerability identified as CVE-2017-5613 represents a critical format string vulnerability affecting cgiemail and cgiecho web applications. This flaw resides in the handling of template files where user-supplied input is processed through format string functions without proper validation or sanitization. The vulnerability stems from the improper use of functions like sprintf, printf, or similar format string operations that accept user-controllable data as format specifiers. When these applications process template files containing format string specifiers, they fail to properly validate or escape the input, creating a path for malicious exploitation.
The technical implementation of this vulnerability involves the exploitation of improper input validation mechanisms within the web application's template processing engine. Attackers can craft malicious template files containing format string specifiers that, when processed by the vulnerable applications, trigger undefined behavior in the underlying C library functions. This misconfiguration allows attackers to manipulate memory layout, read sensitive data from stack memory, or potentially execute arbitrary code on the target system. The vulnerability specifically affects the cgiemail and cgiecho applications which are commonly used for web-based email submission and echo functionality respectively, making them attractive targets for attackers seeking to gain unauthorized access to web servers.
Operationally, this vulnerability presents significant risks to affected systems as remote attackers can leverage it to execute arbitrary code with the privileges of the web server process. The impact extends beyond simple code execution to include potential privilege escalation, data exfiltration, and system compromise. Attackers can exploit this vulnerability to gain persistent access to web servers, install backdoors, or use the compromised system as a launching point for further attacks within the network infrastructure. The remote nature of the attack means that exploitation can occur from any location without requiring physical access to the target system, making it particularly dangerous for web-facing applications.
The vulnerability aligns with CWE-134, which specifically addresses format string vulnerabilities where format string specifiers are derived from untrusted sources. This categorization reflects the core issue of improper input handling in applications that process user-supplied data through format string functions. From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including TA0002 Execution through the use of command injection and TA0006 Credential Access through potential privilege escalation. The attack surface is particularly concerning given that these applications are often deployed in shared hosting environments where multiple users may have access to template configuration files, increasing the likelihood of exploitation.
Mitigation strategies for CVE-2017-5613 should prioritize immediate patching of affected applications to address the underlying format string vulnerability. Organizations should implement proper input validation and sanitization measures that prevent user-controllable data from being processed as format specifiers. The recommended approach includes replacing vulnerable format string functions with safer alternatives that do not accept user input as format specifiers, implementing strict template file validation, and ensuring that all template processing occurs within secure sandboxes. Additionally, network segmentation and access controls should be implemented to limit exposure of vulnerable applications to untrusted users. Regular security audits and code reviews should be conducted to identify similar vulnerabilities in other applications, while monitoring systems should be deployed to detect potential exploitation attempts. The implementation of web application firewalls and input validation rules can provide additional layers of protection against format string exploitation attempts.