CVE-2011-2770 in man2html
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in man2html.cgi.c in man2html 1.6, and possibly other version, allows remote attackers to inject arbitrary web script or HTML via unspecified vectors related to error messages.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/26/2021
The CVE-2011-2770 vulnerability represents a classic cross-site scripting flaw within the man2html utility, specifically in the man2html.cgi.c component of version 1.6 and potentially other iterations. This vulnerability resides in the error message handling mechanisms of the utility that converts manual pages to html format, creating a pathway for malicious actors to execute arbitrary web scripts or HTML code within the context of a victim's browser. The flaw occurs when the application fails to properly sanitize or escape user-supplied input that appears in error messages, allowing attackers to inject malicious content that gets rendered in the browser without adequate protection mechanisms.
The technical nature of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting weaknesses in web applications. The vulnerability operates through the manipulation of error message generation processes where user input is directly incorporated into the response without proper sanitization or encoding. When the man2html utility encounters malformed input or processing errors, it may display error messages that contain unescaped user data, creating an XSS vector. This type of vulnerability is particularly dangerous because it can be exploited through various attack vectors including direct input manipulation, file upload scenarios, or by manipulating parameters that get reflected in error messages.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, deface web pages, steal sensitive information, or redirect users to malicious websites. Since man2html is commonly used in web environments for displaying documentation, the attack surface is broad and includes any web application that utilizes this utility for generating help content or documentation displays. The vulnerability can be exploited by sending malicious payloads through parameters or input fields that are processed by the man2html utility, with the resulting error messages containing the injected scripts. This makes the vulnerability particularly insidious as it can be triggered through legitimate usage patterns, making detection and prevention more challenging.
Mitigation strategies for CVE-2011-2770 should focus on input validation and output encoding practices that align with established security frameworks. Organizations should implement proper sanitization of all user-supplied input before it is processed or displayed in error messages, utilizing encoding techniques such as HTML entity encoding to prevent script execution. The ATT&CK framework categorizes this type of vulnerability under T1203 - Exploitation for Client Execution, highlighting the need for comprehensive input validation and output encoding as primary defensive measures. Updates to the man2html utility to version 1.6.1 or later, which contain fixes for this vulnerability, represent the most effective immediate remediation approach. Additionally, web application firewalls and security scanning tools should be configured to detect and block suspicious input patterns that could lead to XSS exploitation. Regular security assessments and code reviews should include examination of error handling routines to ensure proper sanitization of user data before rendering in web contexts, as this vulnerability demonstrates the critical importance of secure error message handling in preventing client-side attacks.