CVE-2016-4637 in tvOS
Summary
by MITRE
CoreGraphics in Apple iOS before 9.3.3, OS X before 10.11.6, tvOS before 9.2.2, and watchOS before 2.2.2 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted BMP image.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/06/2022
The vulnerability identified as CVE-2016-4637 represents a critical memory corruption flaw within Apple's CoreGraphics framework affecting multiple operating systems including iOS, OS X, tvOS, and watchOS. This issue arises from insufficient input validation when processing BMP image files, creating a pathway for remote attackers to exploit memory corruption vulnerabilities. The flaw exists in the image parsing logic where the system fails to properly validate the structure and content of BMP files before attempting to render them, leading to potential arbitrary code execution or denial of service conditions.
The technical implementation of this vulnerability stems from improper bounds checking and memory management within the CoreGraphics rendering pipeline. When a maliciously crafted BMP image is processed, the system's image decoder does not adequately verify the image headers, pixel data structures, or metadata fields, allowing attackers to manipulate memory locations through carefully constructed image files. This memory corruption occurs during the image decompression and rendering phases, where buffer overflows or use-after-free conditions can be triggered, potentially enabling attackers to execute malicious code with the privileges of the affected application or system process.
The operational impact of CVE-2016-4637 extends beyond simple denial of service scenarios to encompass full system compromise capabilities. Attackers can leverage this vulnerability through various attack vectors including email attachments, web downloads, or malicious websites that serve the crafted BMP images. The vulnerability affects the core graphics rendering infrastructure, making it particularly dangerous as it can be exploited in multiple contexts where image processing occurs. Systems running affected versions become susceptible to remote code execution attacks, potentially allowing threat actors to gain unauthorized access, escalate privileges, or install persistent malware on target devices.
Mitigation strategies for this vulnerability require immediate system updates to the patched versions of Apple operating systems, specifically iOS 9.3.3, OS X 10.11.6, tvOS 9.2.2, and watchOS 2.2.2. Organizations should implement network-level controls to block or scan BMP file attachments and downloads, particularly from untrusted sources. Security teams should monitor for exploitation attempts through network traffic analysis and endpoint detection systems. The vulnerability aligns with CWE-125, which addresses out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write conditions, while also mapping to ATT&CK technique T1059 for command and scripting interpreter execution. Additional defensive measures include implementing application whitelisting policies, restricting image processing capabilities in web browsers, and conducting regular vulnerability assessments to identify unpatched systems within the network infrastructure.