CVE-2017-7846 in Thunderbird
Summary
by MITRE
It is possible to execute JavaScript in the parsed RSS feed when RSS feed is viewed as a website, e.g. via "View -> Feed article -> Website" or in the standard format of "View -> Feed article -> default format". This vulnerability affects Thunderbird < 52.5.2.
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Analysis
by VulDB Data Team • 03/22/2023
This vulnerability resides in the email client Thunderbird and represents a cross-site scripting flaw that emerges when processing RSS feeds. The security issue manifests when users navigate to RSS feed content through the application's interface, specifically via the "View -> Feed article -> Website" or "View -> Feed article -> default format" pathways. The vulnerability stems from insufficient input sanitization during the parsing of RSS feed content, allowing malicious JavaScript code embedded within feed items to execute in the context of the user's browser session.
The technical implementation of this flaw involves the RSS feed parser not properly escaping or sanitizing user-supplied content before rendering it in web contexts. When Thunderbird processes an RSS feed containing malicious script tags, the application fails to neutralize these potentially harmful elements during the rendering process. This creates an environment where attacker-controlled JavaScript can execute with the privileges of the user's browser session, potentially leading to session hijacking, data exfiltration, or further exploitation of the victim's system. The vulnerability specifically affects versions prior to 52.5.2, indicating that the issue was addressed through proper input validation and output sanitization measures in the application's feed parsing components.
The operational impact of this vulnerability extends beyond simple script execution, as it can be leveraged in sophisticated attack scenarios. An attacker who controls an RSS feed can craft malicious content that, when viewed by a victim using an affected Thunderbird version, executes arbitrary JavaScript code. This could enable attackers to steal cookies, perform actions on behalf of the user, or redirect them to malicious websites. The vulnerability particularly affects users who regularly consume RSS feeds through Thunderbird, making it a significant concern for those who rely on the application for news aggregation or content consumption. The attack vector requires user interaction through the specific viewing pathways mentioned, but once triggered, the consequences can be severe.
Mitigation strategies for this vulnerability focus on both immediate remediation and defensive measures. The primary solution involves updating Thunderbird to version 52.5.2 or later, where the feed parsing logic has been modified to properly sanitize input before rendering. Organizations should implement automated patch management systems to ensure all Thunderbird installations remain current with security updates. Additionally, users should be educated about the risks of viewing untrusted RSS feeds and the importance of maintaining updated software. Network-level defenses such as content filtering systems can provide additional protection by blocking known malicious feed content, though these measures are secondary to proper application-level fixes. The vulnerability aligns with CWE-79, which addresses cross-site scripting flaws, and could be categorized under ATT&CK technique T1203 for legitimate program execution, as it exploits the application's own rendering capabilities to execute malicious code.