CVE-2017-0923 in Community Edition
Summary
by MITRE
Gitlab Community Edition version 9.1 is vulnerable to lack of input validation in the IPython notebooks component resulting in persistent cross site scripting.
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Analysis
by VulDB Data Team • 01/15/2020
The vulnerability identified as CVE-2017-0923 affects Gitlab Community Edition version 9.1 and stems from inadequate input validation within the IPython notebooks component. This flaw represents a critical security weakness that allows malicious actors to inject persistent cross-site scripting payloads into the system. The vulnerability specifically impacts the handling of user-supplied data within the notebook functionality, where insufficient sanitization permits the execution of malicious scripts in the context of other users' browsers. The issue arises from the application's failure to properly validate and sanitize input parameters before processing them within the IPython notebook rendering environment.
The technical exploitation of this vulnerability occurs when an attacker uploads or modifies an IPython notebook file containing malicious JavaScript code. The vulnerable component fails to adequately filter or escape special characters and script tags in the notebook content, allowing the malicious code to persist within the application's data storage. When other users access the affected notebook, their browsers execute the injected scripts, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the victims. This persistent nature of the vulnerability means that the malicious payload remains active until manually removed from the system, creating a long-term security risk for all users who interact with the compromised notebooks.
The operational impact of CVE-2017-0923 extends beyond simple script execution, as it enables attackers to establish persistent footholds within Gitlab environments where notebooks are actively used. Organizations utilizing Gitlab for collaborative data science projects, research documentation, or educational purposes face significant risks when this vulnerability exists. The attack surface is particularly concerning in environments where multiple users share repositories containing IPython notebooks, as a single compromised file can affect numerous users. The vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws, and demonstrates how insufficient input validation creates opportunities for attackers to manipulate application behavior through user-controllable data. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1059.007 for Command and Scripting Interpreter, specifically targeting web applications through browser-based scripting.
Mitigation strategies for CVE-2017-0923 require immediate attention through software updates and configuration hardening. The most effective remediation involves upgrading to Gitlab Community Edition version 9.2 or later, where the input validation issues have been addressed through proper sanitization of notebook content. Organizations should implement comprehensive input validation at multiple layers, including server-side filtering of notebook file contents and client-side sanitization of user inputs. Additional protective measures include restricting notebook upload permissions, implementing content security policies, and regularly auditing notebook repositories for malicious content. Security teams should also consider deploying web application firewalls to detect and block suspicious script injection attempts, while maintaining detailed logging of notebook access and modification activities to identify potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation in web applications and the potential consequences of inadequate sanitization of user-controllable data within collaborative platforms.