CVE-2017-5463 in Firefox
Summary
by MITRE
Android intents can be used to launch Firefox for Android in reader mode with a user specified URL. This allows an attacker to spoof the contents of the addressbar as displayed to users. Note: This attack only affects Firefox for Android. Other operating systems are not affected. This vulnerability affects Firefox < 53.
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Analysis
by VulDB Data Team • 08/26/2024
The vulnerability described in CVE-2017-5463 represents a sophisticated user interface deception attack targeting Firefox for Android users. This flaw exploits the Android intent system, which serves as a fundamental mechanism for inter-application communication within the Android operating environment. When Firefox for Android processes incoming intents with specific parameters, it can be instructed to open a URL in reader mode without proper validation of the source or content of that URL. This creates a dangerous scenario where malicious actors can craft specially formatted intents that trick users into believing they are visiting a legitimate website, while actually displaying content from an entirely different source.
The technical implementation of this vulnerability stems from inadequate input validation within Firefox's intent handling mechanism. When the application receives an Android intent containing a URL parameter, it fails to properly verify the authenticity or legitimacy of that URL before rendering it in reader mode. This validation gap allows attackers to manipulate the address bar display through carefully crafted intent payloads. The vulnerability specifically affects Firefox versions prior to 53, indicating that this was a known issue that required a software update to resolve. The attack vector leverages the Android Intent system which is designed to enable seamless application interoperability, but in this case becomes a conduit for malicious activity.
From an operational impact perspective, this vulnerability creates a significant trust relationship violation between the user and the browser application. Users are deceived into believing they are visiting a legitimate website due to the spoofed address bar display, while the actual content being rendered may be entirely different and potentially malicious. This type of attack falls under the category of phishing and social engineering, where the deception is made more convincing through the visual manipulation of the browser interface. The vulnerability is particularly dangerous because it exploits user trust in the browser's address bar as a security indicator, which is a fundamental security feature that users rely upon for website authentication.
The implications of this vulnerability extend beyond simple deception to encompass potential data theft, malware delivery, and credential harvesting. Attackers could use this technique to create convincing fake login pages or malicious content delivery mechanisms that appear legitimate to users. This flaw demonstrates the importance of proper input validation and the principle of least privilege in application design, where applications should not blindly trust external inputs without proper sanitization and verification. The vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic case of how Android intent system misconfiguration can create security weaknesses. From an attacker's perspective, this vulnerability maps to techniques described in the ATT&CK framework under defensive evasion and credential access phases, where adversaries seek to manipulate user perception and extract sensitive information.
The remediation for this vulnerability required Firefox developers to implement proper intent validation and URL sanitization within the Android application. This involved strengthening the input validation mechanisms that process external intents and ensuring that URLs are properly verified before being rendered in reader mode. Users were advised to upgrade to Firefox version 53 or later, which contained the necessary security patches. Organizations should have implemented awareness training to help users recognize potential signs of such deception attacks and maintain updated browser software to protect against known vulnerabilities. The incident underscores the critical importance of security testing for mobile applications that leverage platform-specific communication mechanisms and demonstrates how seemingly benign features can become security risks when not properly implemented.