CVE-2018-4377 in Safari
Summary
by MITRE
A cross-site scripting issue existed in Safari. This issue was addressed with improved URL validation. This issue affected versions prior to iOS 12.1, watchOS 5.1, Safari 12.0.1, iTunes 12.9.1, iCloud for Windows 7.8.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/08/2020
The vulnerability described in CVE-2018-4377 represents a cross-site scripting flaw that existed within Apple Safari web browser and related software components. This security weakness allowed malicious actors to potentially execute arbitrary scripts in the context of a user's browser session, posing significant risks to web application security and user privacy. The issue specifically affected a broad range of Apple products and services, including mobile operating systems, desktop applications, and cloud services that utilized Safari as their primary web rendering engine. The vulnerability's presence in these widely-used platforms created substantial exposure across Apple's ecosystem, affecting millions of users who relied on these applications for daily computing activities.
The technical root cause of this vulnerability lies in inadequate URL validation mechanisms within Safari's web rendering engine. When processing certain malformed or specially crafted URLs, the browser failed to properly sanitize input parameters that could be interpreted as executable script code. This validation gap created an environment where maliciously constructed web addresses could trigger XSS attacks, allowing attackers to inject and execute unauthorized JavaScript code within the user's browser context. The flaw essentially allowed attackers to bypass normal security boundaries that should prevent script execution from untrusted sources, making it particularly dangerous for web applications that rely on user input validation. This type of vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is a well-documented weakness in web application security that has been consistently ranked among the top security risks by organizations like OWASP.
The operational impact of CVE-2018-4377 extended far beyond simple script injection, as it could enable attackers to perform a wide range of malicious activities including session hijacking, data theft, and unauthorized access to user accounts. Users who visited compromised websites or clicked on malicious links could have their browser sessions compromised, potentially leading to the theft of sensitive information such as login credentials, personal data, or financial information. The vulnerability's presence in multiple Apple platforms including iOS, watchOS, and desktop applications meant that attackers could target users across different device types, increasing the attack surface and potential damage. Additionally, the affected versions included critical components like iCloud for Windows, which meant that users running older versions of these applications were exposed to similar risks, regardless of their primary device platform. This cross-platform exposure created a complex security landscape where users needed to maintain updated software across multiple systems to remain protected.
Apple's response to this vulnerability involved implementing improved URL validation mechanisms that properly sanitized input parameters and prevented malicious script execution. The company released updates for iOS 12.1, watchOS 5.1, Safari 12.0.1, iTunes 12.9.1, and iCloud for Windows 7.8, which addressed the specific validation gaps that allowed XSS attacks. These patches demonstrated the importance of proper input validation and sanitization in web applications, aligning with security best practices recommended by organizations like NIST and the CWE community. The remediation approach focused on strengthening the browser's URL parsing and validation logic to ensure that potentially malicious content could not be executed within the browser context. This fix represented a critical security improvement that aligned with the ATT&CK framework's concept of command and control through web-based attacks, where proper validation of user inputs is essential to prevent malicious code execution. Organizations and users were advised to immediately apply these updates to protect against potential exploitation, as the vulnerability could have been actively exploited in the wild prior to the release of these security patches. The incident highlighted the ongoing need for robust input validation and security testing in web applications, particularly in widely-used browsers and operating systems where the potential impact of such vulnerabilities can be extensive and far-reaching.