CVE-2021-30942 Overview
CVE-2021-30942 is a memory corruption vulnerability affecting Apple's ColorSync framework, specifically in the processing of ICC (International Color Consortium) color profiles. The vulnerability arises from improper input validation when parsing maliciously crafted ICC profiles embedded in image files. Successful exploitation could allow an attacker to achieve arbitrary code execution on affected Apple devices when a user opens a specially crafted image.
Critical Impact
Processing a maliciously crafted image may lead to arbitrary code execution, potentially allowing attackers to gain control over affected Apple devices across macOS, iOS, iPadOS, tvOS, and watchOS platforms.
Affected Products
- Apple macOS Big Sur (versions prior to 11.6.2)
- Apple macOS Monterey (versions prior to 12.1)
- Apple macOS Catalina (prior to Security Update 2021-008)
- Apple iOS and iPadOS (versions prior to 15.2)
- Apple tvOS (versions prior to 15.2)
- Apple watchOS (versions prior to 8.3)
Discovery Timeline
- 2021-08-24 - CVE-2021-30942 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2021-30942
Vulnerability Analysis
This vulnerability is classified as CWE-787 (Out-of-bounds Write), a type of memory corruption flaw that occurs when ColorSync processes ICC profile data without proper boundary checks. ICC profiles are data structures that define color space characteristics and are commonly embedded in image files like JPEG, PNG, and TIFF formats. When the vulnerable ColorSync component parses a malformed ICC profile, it fails to properly validate input boundaries, leading to memory corruption.
The vulnerability requires local access and user interaction to exploit—specifically, the victim must open a maliciously crafted image file. Once triggered, the memory corruption can be leveraged to hijack program execution flow and achieve arbitrary code execution with the privileges of the affected application or user session.
Root Cause
The root cause of CVE-2021-30942 lies in insufficient input validation within Apple's ColorSync framework when processing ICC profile data. The parsing routines did not adequately verify the size and structure of ICC profile elements before writing data to memory buffers. This oversight allows an attacker to craft an ICC profile with malformed dimensions or offsets that cause the parser to write data beyond the boundaries of allocated memory regions.
Attack Vector
The attack vector for this vulnerability is local, requiring user interaction. An attacker would need to:
- Craft a malicious image file (JPEG, PNG, TIFF, or other supported format) containing a specially crafted ICC profile
- Deliver the malicious image to the target through email attachment, web download, messaging application, or other file transfer mechanisms
- Convince the victim to open or preview the image file
When the affected system processes the image, the ColorSync framework automatically parses the embedded ICC profile, triggering the out-of-bounds write condition. The vulnerability affects multiple rendering contexts across Apple's ecosystem, including image previews in Finder, Mail, Messages, and third-party applications that rely on system-level image processing.
Detailed technical analysis is available in the Packet Storm Security advisory.
Detection Methods for CVE-2021-30942
Indicators of Compromise
- Unexpected crashes or abnormal behavior in applications processing image files
- System log entries indicating ColorSync or ImageIO framework errors
- Memory access violations related to ICC profile parsing operations
- Suspicious image files with unusually large or malformed ICC profile metadata
Detection Strategies
- Monitor for abnormal process behavior following image file access, particularly memory corruption indicators
- Implement file integrity monitoring for image processing components within the ColorSync framework
- Deploy endpoint detection and response (EDR) solutions capable of identifying memory corruption exploitation attempts
- Analyze image files in sandboxed environments before allowing processing on production systems
Monitoring Recommendations
- Enable crash reporting and analyze crash dumps for patterns consistent with ICC profile exploitation
- Monitor system logs for ColorSync-related errors or warnings across affected Apple platforms
- Implement network monitoring to detect delivery of potentially malicious image files
- Configure SentinelOne agents to alert on suspicious memory manipulation patterns in image processing workflows
How to Mitigate CVE-2021-30942
Immediate Actions Required
- Update all affected Apple devices to the patched versions immediately
- Apply Security Update 2021-008 for macOS Catalina systems
- Upgrade macOS Big Sur to version 11.6.2 or later
- Upgrade macOS Monterey to version 12.1 or later
- Upgrade iOS and iPadOS to version 15.2 or later
- Upgrade tvOS to version 15.2 or later and watchOS to version 8.3 or later
Patch Information
Apple has released security updates that address this vulnerability through improved input validation in the ICC profile processing code. The following security advisories contain detailed patch information:
- Apple Security Update HT212975 - macOS Big Sur 11.6.2
- Apple Security Update HT212976 - macOS Monterey 12.1
- Apple Security Update HT212978 - Security Update 2021-008 Catalina
- Apple Security Update HT212979 - iOS 15.2 and iPadOS 15.2
- Apple Security Update HT212980 - tvOS 15.2
- Apple Security Update HT212981 - watchOS 8.3
Workarounds
- Exercise caution when opening image files from untrusted or unknown sources
- Implement email gateway filtering to scan and quarantine suspicious image attachments
- Consider using sandboxed applications for previewing images from untrusted sources
- Deploy endpoint protection solutions that can detect and block exploitation attempts
# Check current macOS version to verify patch status
sw_vers -productVersion
# For macOS, trigger software update check
softwareupdate --list
# Install all available security updates
softwareupdate --install --all
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
