CVE-2015-7208 in Firefox
Summary
by MITRE
Mozilla Firefox before 43.0 stores cookies containing vertical tab characters, which allows remote attackers to obtain sensitive information by reading HTTP Cookie headers.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability identified as CVE-2015-7208 represents a significant security flaw in Mozilla Firefox versions prior to 43.0, specifically related to how the browser handles cookie storage and transmission. This issue stems from Firefox's improper handling of vertical tab characters within cookie values, creating a potential information disclosure risk that could be exploited by remote attackers. The flaw manifests when Firefox stores cookies containing vertical tab characters and subsequently includes these cookies in HTTP header transmissions, potentially exposing sensitive data to unauthorized parties.
The technical root cause of this vulnerability lies in Firefox's cookie processing implementation, which fails to properly sanitize or normalize cookie values containing vertical tab characters. When such cookies are transmitted in HTTP requests, the vertical tab characters can interfere with the parsing and interpretation of cookie headers, potentially allowing attackers to manipulate or extract information from the cookie data. This behavior creates a scenario where cookie data may be interpreted differently by various server components, leading to potential information leakage. The vulnerability specifically affects the HTTP cookie header parsing mechanism, where the presence of vertical tab characters can cause unexpected behavior in cookie handling across different systems and applications.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable sophisticated attack vectors including session hijacking, cross-site scripting exploitation, and unauthorized access to user sessions. Attackers can leverage this flaw to craft malicious cookies containing vertical tab characters that, when processed by vulnerable Firefox versions, may reveal session tokens or other sensitive information. The vulnerability operates at the application layer and can be exploited through web-based attacks, making it particularly dangerous in environments where users browse untrusted websites or where web applications rely on cookie-based authentication mechanisms. This type of vulnerability falls under the CWE-20 category for "Improper Input Validation" and aligns with ATT&CK technique T1185 for "Man in the Middle" attacks.
Mitigation strategies for CVE-2015-7208 primarily involve upgrading to Firefox version 43.0 or later, where the cookie handling has been corrected to properly sanitize vertical tab characters. Organizations should implement comprehensive patch management procedures to ensure all Firefox installations are updated promptly. Additionally, network administrators can deploy web application firewalls that monitor and filter cookie headers for suspicious character sequences, though this represents a secondary defense measure. Security teams should also conduct regular vulnerability assessments to identify any remaining instances of older Firefox versions within their environments and establish monitoring procedures to detect potential exploitation attempts. The fix implemented in Firefox 43.0 addresses the core issue by normalizing cookie values during storage and ensuring that vertical tab characters are properly handled during HTTP header construction, preventing the information disclosure that previously occurred.