CVE-2018-11646 in WebKit
Summary
by MITRE
webkitFaviconDatabaseSetIconForPageURL and webkitFaviconDatabaseSetIconURLForPageURL in UIProcess/API/glib/WebKitFaviconDatabase.cpp in WebKit, as distributed in Safari Technology Preview Release 57, mishandle an unset pageURL, leading to an application crash.
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Analysis
by VulDB Data Team • 12/01/2024
The vulnerability identified as CVE-2018-11646 resides within the WebKit rendering engine's favicon database functionality, specifically in the UIProcess API implementation for GLib-based applications. This issue affects Safari Technology Preview Release 57 and demonstrates a critical flaw in how the webkitFaviconDatabaseSetIconForPageURL and webkitFaviconDatabaseSetIconURLForPageURL functions handle page URL parameters. The vulnerability stems from insufficient input validation and parameter checking within the favicon database management system, creating a condition where an unset or null pageURL parameter can trigger an application crash. This represents a classic buffer over-read or null pointer dereference scenario that can be exploited to cause denial of service conditions.
The technical implementation flaw occurs when the WebKit favicon database component receives a request to set an icon for a page URL without properly validating whether the pageURL parameter has been initialized or contains valid data. The functions in question fail to perform adequate null checks or parameter validation before proceeding with the database operations, leading to memory access violations when attempting to process the unset pageURL. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions, and can be categorized as a software fault that results in improper handling of uninitialized or invalid input parameters. The lack of proper error handling in these API functions creates a pathway for malicious actors to craft specific requests that will cause the application to crash when processing favicon data.
The operational impact of this vulnerability extends beyond simple application instability, as it can be leveraged to create denial of service conditions against WebKit-based applications including Safari and other browser implementations that utilize this component. When exploited, the crash can occur during normal browsing operations when the browser attempts to cache or update favicon information for web pages, potentially affecting user experience and system availability. Attackers could craft malicious web pages or manipulate favicon data requests to trigger these crashes, leading to repeated application instability and potential service disruption. This vulnerability is particularly concerning in environments where WebKit-based applications are used extensively, as it could be exploited to repeatedly crash browser sessions or web applications that depend on the favicon database functionality.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and parameter checking within the affected WebKit components. Developers should ensure that all pageURL parameters are validated before processing, with proper null checks and error handling mechanisms in place. The fix should involve adding explicit validation routines that verify the existence and validity of pageURL parameters before proceeding with database operations. Additionally, implementing proper exception handling and graceful degradation mechanisms would prevent crashes from occurring when invalid parameters are encountered. Organizations should also consider applying the latest WebKit updates and patches that address this specific vulnerability, as the issue was resolved in subsequent releases. From an operational security perspective, monitoring for unusual favicon-related crashes or error patterns in WebKit-based applications can help identify potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a fundamental security weakness that can be addressed through proper defensive programming practices and comprehensive input validation mechanisms.