CVE-2018-1000078 in Ruby
Summary
by MITRE
RubyGems version Ruby 2.2 series: 2.2.9 and earlier, Ruby 2.3 series: 2.3.6 and earlier, Ruby 2.4 series: 2.4.3 and earlier, Ruby 2.5 series: 2.5.0 and earlier, prior to trunk revision 62422 contains a Cross Site Scripting (XSS) vulnerability in gem server display of homepage attribute that can result in XSS. This attack appear to be exploitable via the victim must browse to a malicious gem on a vulnerable gem server. This vulnerability appears to have been fixed in 2.7.6.
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Analysis
by VulDB Data Team • 02/21/2023
The vulnerability identified as CVE-2018-1000078 represents a cross site scripting flaw within the RubyGems package management system affecting multiple Ruby versions including 2.2.9 and earlier, 2.3.6 and earlier, 2.4.3 and earlier, and 2.5.0 and earlier. This security weakness resides in the gem server's handling of the homepage attribute display, creating an avenue for malicious code execution when users navigate to compromised gems hosted on vulnerable servers. The vulnerability operates under the Common Weakness Enumeration classification of CWE-79, which specifically addresses cross site scripting vulnerabilities where untrusted data is improperly incorporated into web pages without proper sanitization or encoding mechanisms. The attack vector requires user interaction through browser navigation to a malicious gem hosted on a vulnerable gem server, making this a client-side exploitation scenario that aligns with ATT&CK technique T1203 for Exploitation for Client Execution.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the RubyGems server component responsible for rendering gem metadata including homepage URLs. When a gem server displays the homepage attribute of a gem package, it fails to properly escape or sanitize user-supplied URL content, allowing malicious JavaScript code embedded within the homepage field to execute in the context of the victim's browser. This flaw specifically impacts the gem server's display functionality rather than the gem installation process, making it particularly dangerous in environments where developers browse gem repositories regularly. The vulnerability's exploitation requires that users actively navigate to a malicious gem page, which means that while the attack is relatively straightforward to execute, it depends on user behavior and trust in the gem repository being accessed.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including credential theft, session hijacking, or redirection to phishing sites. Since RubyGems serves as a critical component in the Ruby ecosystem and is widely used by developers for package management, the potential attack surface is significant. The vulnerability's presence in multiple Ruby series versions indicates a widespread exposure affecting numerous development environments and applications that rely on Ruby package management. Organizations using affected Ruby versions are at risk of having their developers' browsers compromised when they browse gem repositories, particularly those that may host malicious packages or where attackers have compromised gem submissions.
Mitigation strategies for CVE-2018-1000078 primarily focus on upgrading to RubyGems version 2.7.6 or later, which contains the necessary patches to address the XSS vulnerability. System administrators and developers should immediately assess their Ruby environments to identify affected versions and implement the upgrade process as a priority. Additional protective measures include implementing content security policies that restrict script execution in gem server contexts, validating and sanitizing all gem metadata before display, and monitoring gem repositories for suspicious submissions. Organizations should also consider implementing network-level controls to prevent access to known malicious gem repositories and establish secure development practices that include regular security assessments of package dependencies. The vulnerability's resolution demonstrates the importance of maintaining current software versions and the critical role of package management security in protecting development ecosystems against client-side attacks.