CVE-2017-8920 in CGI:IRC
Summary
by MITRE
irc.cgi in CGI:IRC before 0.5.12 reflects user-supplied input from the R parameter without proper output encoding, aka XSS.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/08/2022
The vulnerability identified as CVE-2017-8920 affects CGI:IRC versions prior to 0.5.12 and represents a classic cross-site scripting flaw that exploits improper input validation and output encoding mechanisms. This vulnerability exists within the irc.cgi script which processes user input through the R parameter, creating an avenue for malicious actors to inject arbitrary web scripts into the application's response. The flaw stems from the application's failure to properly sanitize or encode user-supplied data before reflecting it back to the user's browser, thereby enabling attackers to execute malicious code within the context of the victim's session.
The technical implementation of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities where input data is not properly escaped or encoded before being rendered in web pages. The R parameter serves as the primary attack vector, allowing an attacker to craft malicious payloads that exploit the lack of output encoding in the irc.cgi script. When a victim visits a maliciously crafted URL containing the XSS payload within the R parameter, the vulnerable application reflects the malicious script back to the victim's browser, executing the attacker's code in the victim's context with the privileges of the victim's session.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to perform session hijacking, steal sensitive cookies, redirect users to malicious sites, or even modify the content displayed to authenticated users. The vulnerability affects any user who interacts with the vulnerable CGI:IRC application, particularly those who might be tricked into clicking malicious links or visiting compromised web pages. Attackers can leverage this vulnerability to escalate privileges within the application context, potentially gaining unauthorized access to user sessions or sensitive information.
Mitigation strategies for this vulnerability primarily involve implementing proper output encoding and input validation mechanisms within the irc.cgi script. The most effective approach is to sanitize all user-supplied input through proper encoding before reflecting it back to the user's browser, which aligns with the remediation recommendations found in the OWASP XSS Prevention Cheat Sheet. Additionally, implementing a Content Security Policy (CSP) header can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be executed. The vulnerability also maps to ATT&CK technique T1203, which covers "Exploitation for Client Execution" where adversaries leverage vulnerabilities in applications to execute malicious code in the victim's browser environment. Updates to CGI:IRC version 0.5.12 or later should be implemented immediately to address this vulnerability and prevent exploitation by malicious actors.