CVE-2020-9955 in tvOS
Summary
by MITRE • 04/03/2021
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in watchOS 7.0, tvOS 14.0, iOS 14.0 and iPadOS 14.0, macOS Big Sur 11.0.1. Processing a maliciously crafted image may lead to arbitrary code execution.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/08/2021
The vulnerability identified as CVE-2020-9955 represents a critical out-of-bounds write flaw that existed within Apple's operating systems, specifically affecting iOS, iPadOS, watchOS, and tvOS versions prior to their respective security updates. This issue stems from insufficient bounds checking mechanisms when processing image files, creating a pathway for malicious actors to exploit the system through crafted image payloads. The vulnerability falls under the category of memory safety issues and is classified as a buffer overflow condition that could be leveraged for arbitrary code execution. The flaw was particularly concerning given that it affected multiple Apple platforms, including mobile devices, wearable technology, and television operating systems, indicating a widespread potential impact across Apple's ecosystem.
Technical exploitation of this vulnerability occurs when the affected operating systems attempt to process maliciously crafted image files that contain malformed data structures. The insufficient bounds checking allows an attacker to write data beyond the allocated memory boundaries of the image processing functions, potentially overwriting adjacent memory locations. This memory corruption can lead to unpredictable behavior including application crashes, system instability, or more critically, the execution of arbitrary code with the privileges of the affected process. The vulnerability specifically impacts image parsing libraries within Apple's operating systems, where image files are decoded and rendered. Attackers could craft images with specially designed metadata or pixel data that would trigger the out-of-bounds write condition during normal image processing operations. This type of vulnerability is particularly dangerous because it can be triggered through normal user interactions, such as viewing an image in a gallery application or receiving an image through messaging applications.
The operational impact of CVE-2020-9955 extends across multiple attack vectors and user scenarios, making it a significant concern for organizations and individual users alike. Mobile devices running affected versions could be compromised simply by viewing or interacting with malicious images, whether through email attachments, social media content, messaging applications, or web browsing activities. The vulnerability's exploitation potential aligns with attack techniques described in the attack pattern taxonomy, particularly those involving code injection and privilege escalation through memory corruption. Organizations using Apple devices for business operations face increased risk of targeted attacks, especially in environments where users might encounter untrusted image content. The cross-platform nature of the vulnerability means that attackers could potentially target users across different Apple device categories, expanding the attack surface and making comprehensive protection more challenging. Security researchers have noted that such out-of-bounds write vulnerabilities often serve as initial access vectors for more sophisticated attacks, as they can be used to establish a foothold for further exploitation.
Apple addressed this vulnerability through comprehensive security updates released as part of iOS 14.0, iPadOS 14.0, watchOS 7.0, and tvOS 14.0, along with macOS Big Sur 11.0.1. The fix implemented improved bounds checking mechanisms within the image processing libraries, ensuring that all image data is properly validated before memory allocation occurs. These updates represent a fundamental improvement in memory safety controls and demonstrate Apple's commitment to addressing security vulnerabilities in their operating systems. Organizations should prioritize immediate deployment of these security updates across all affected Apple platforms to mitigate the risk of exploitation. Additional protective measures include implementing network-based filtering to block suspicious image content, conducting user awareness training about the risks of opening untrusted image files, and monitoring for potential exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date security patches and following industry best practices for vulnerability management. Security professionals should note that this vulnerability aligns with common weakness enumerations such as CWE-787, which specifically addresses out-of-bounds write conditions, and represents a classic example of how memory safety issues can compromise system integrity and user security.