CVE-2024-10460 in Thunderbird
Summary
by MITRE • 10/29/2024
The origin of an external protocol handler prompt could have been obscured using a data: URL within an `iframe`. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.
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Analysis
by VulDB Data Team • 03/02/2025
This vulnerability represents a sophisticated phishing attack vector that exploits the trust relationship between web browsers and external protocol handlers. The flaw allows malicious actors to obscure the true origin of protocol handler prompts by embedding data URLs within iframes, effectively masking the actual source of the request. This technique undermines user trust and creates opportunities for deceptive interactions that could lead to credential theft or unauthorized actions. The vulnerability specifically impacts Mozilla Firefox and Thunderbird products across multiple versions, with the issue persisting in both regular releases and extended support releases. The technical implementation involves the manipulation of browser security boundaries where data URLs within iframe contexts can bypass normal origin validation mechanisms that typically protect users from suspicious protocol handler requests.
The core technical flaw resides in how browsers process external protocol handler prompts when these requests originate from nested iframe contexts containing data URLs. When a user encounters a malicious page, the browser may display a protocol handler prompt that appears to come from a trusted domain due to the way data URLs are processed within iframe structures. This creates a scenario where legitimate-looking prompts can actually originate from malicious sources, exploiting the browser's trust model for external protocol handlers. The vulnerability leverages the fact that data URLs are treated as having a unique origin that can be manipulated to appear as if they originate from different domains than their actual source. This manipulation occurs at the browser's security layer where the origin determination for protocol handler prompts becomes ambiguous when data URLs are involved in iframe contexts.
The operational impact of this vulnerability extends beyond simple phishing attempts to encompass more serious security risks including credential harvesting and unauthorized system actions. Attackers can craft malicious web pages that, when viewed by users, present protocol handler prompts that appear to originate from trusted domains such as banking or email services. Users who interact with these prompts may unknowingly grant permissions to malicious applications or services, potentially leading to account compromise or system infiltration. The vulnerability affects both web browsers and email clients, creating a broader attack surface that requires users to be vigilant across multiple applications. Security researchers have identified that this issue is particularly dangerous because it operates at the user interaction level where human judgment is required to make security decisions, making it more difficult to defend against through automated means.
Mitigation strategies for this vulnerability require both immediate patching and user education approaches to address the root cause. Organizations should prioritize updating all affected Firefox and Thunderbird installations to the latest versions that contain the security fixes. The patches typically involve strengthening the origin validation logic for protocol handler prompts to ensure that data URLs within iframe contexts cannot be used to obscure the true source of requests. Browser vendors have implemented modifications to how these security prompts are displayed and validated, ensuring that the actual origin of requests is clearly visible to users regardless of iframe or data URL manipulations. Additionally, security teams should consider implementing browser security policies that restrict the use of data URLs in potentially dangerous contexts and educate users about recognizing suspicious protocol handler prompts. The vulnerability aligns with attack patterns documented in the attack tree framework where attackers exploit trust relationships and user interaction models to bypass security controls. This issue also relates to common weakness enumerations such as CWE-798, which deals with the use of hard-coded credentials, and CWE-20, which addresses input validation issues, as the vulnerability essentially exploits the trust model through manipulated input contexts.