CVE-2009-1689 in Safari
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in WebKit in Apple Safari before 4.0, iPhone OS 1.0 through 2.2.1, and iPhone OS for iPod touch 1.1 through 2.2.1 allows remote attackers to inject arbitrary web script or HTML via vectors involving submission of a form to the about:blank URL, leading to security-context replacement.
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Analysis
by VulDB Data Team • 09/06/2019
This cross-site scripting vulnerability exists within the WebKit rendering engine used by Apple Safari and iOS browsers, affecting versions prior to 4.0 and iPhone OS 1.0 through 2.2.1. The flaw stems from insufficient input validation and sanitization when processing form submissions to the about:blank URL, which creates a security context replacement scenario that allows malicious actors to execute arbitrary scripts in the victim's browser context. The vulnerability specifically leverages the way WebKit handles navigation and security boundaries when transitioning between different document contexts, particularly when the about:blank pseudo-URL is used as a target for form submissions.
The technical implementation of this vulnerability involves the manipulation of browser security models through crafted form submissions that exploit how the browser handles document transitions and security contexts. When a form is submitted to about:blank, the browser's security mechanisms fail to properly validate or sanitize the input parameters, allowing attackers to inject malicious JavaScript code that executes in the context of the victim's current browsing session. This represents a classic security context replacement attack where the browser's expected behavior is subverted to execute unauthorized code. The vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and specifically demonstrates weaknesses in input validation and output encoding within web browser implementations.
The operational impact of this vulnerability is significant as it enables remote code execution in the context of a victim's browser session without requiring any user interaction beyond visiting a malicious website. Attackers can craft web pages that automatically submit forms to about:blank URLs with malicious payloads, effectively bypassing the same-origin policy and other browser security mechanisms. This allows for session hijacking, credential theft, data exfiltration, and the execution of arbitrary commands on the victim's device. The attack vector is particularly dangerous because it requires no user interaction beyond visiting a compromised site, making it a prime candidate for drive-by download attacks and social engineering campaigns. The vulnerability affects not just desktop Safari browsers but also mobile iOS devices, expanding the attack surface significantly.
Mitigation strategies for this vulnerability include immediate patching of affected systems to upgrade to Safari 4.0 and newer iPhone OS versions that contain the necessary security fixes. Organizations should implement comprehensive web application firewalls and content security policies to prevent the execution of unauthorized scripts, while also deploying input validation mechanisms that sanitize all form inputs and prevent the injection of malicious code. Browser security enhancements such as sandboxing, strict content security policies, and automatic updates should be enabled to reduce the risk of exploitation. Additionally, security awareness training for users can help prevent visits to malicious websites, though this is less effective against automated attacks. The vulnerability demonstrates the importance of proper security context management in browser implementations and aligns with ATT&CK technique T1059.007 for scripting languages and T1566 for phishing attacks that leverage browser vulnerabilities.