CVE-2021-30917: Apple iPadOS RCE Vulnerability

CVE-2021-30917 Overview

A memory corruption vulnerability exists in Apple's ICC (International Color Consortium) profile processing functionality within the ColorSync framework. The flaw stems from improper input validation when handling specially crafted ICC profiles embedded in image files. Successful exploitation of this vulnerability could allow an attacker to achieve arbitrary code execution with the privileges of the current user by convincing them to open a malicious image file.

Critical Impact

Processing a maliciously crafted image may lead to arbitrary code execution across multiple Apple platforms including iOS, iPadOS, macOS, tvOS, and watchOS.

Affected Products

• Apple iOS versions prior to 15.1 and 14.8.1
• Apple iPadOS versions prior to 15.1 and 14.8.1
• Apple macOS Monterey prior to 12.0.1
• Apple macOS Big Sur prior to 11.6.1
• Apple macOS Catalina (requires Security Update 2021-007)
• Apple tvOS versions prior to 15.1
• Apple watchOS versions prior to 8.1

Discovery Timeline

• August 24, 2021 - CVE-2021-30917 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2021-30917

Vulnerability Analysis

The vulnerability resides in Apple's ColorSync framework, specifically within the CMMNDimLinear::Interpolate function responsible for processing ICC color profiles. ICC profiles are standardized data formats used to ensure consistent color representation across different devices and software. When parsing malformed ICC profile data embedded within image files, the affected function fails to properly validate input parameters before performing memory operations.

The flaw involves the use of uninitialized memory during the interpolation calculations for multi-dimensional color lookup tables. An attacker can craft a malicious ICC profile with specific parameters that cause the vulnerable function to read from or write to uninitialized memory regions, potentially leading to memory corruption and subsequent code execution.

This vulnerability requires local access and user interaction, meaning a victim must open or preview a maliciously crafted image file containing the exploit payload. Common attack scenarios include email attachments, malicious downloads, or compromised websites serving poisoned image content.

Root Cause

The root cause of CVE-2021-30917 is improper input validation (CWE-20) in the ICC profile parsing code. The ColorSync framework's CMMNDimLinear::Interpolate function did not adequately validate profile parameters before using them in memory operations, resulting in uninitialized memory access. Apple addressed this issue by implementing improved input validation to ensure ICC profile data is properly sanitized before processing.

Attack Vector

The attack vector for this vulnerability is local, requiring user interaction to open a malicious image file. An attacker would typically:

1. Craft a malicious image file (JPEG, PNG, TIFF, or other formats supporting ICC profiles) containing a specially crafted ICC profile
2. Distribute the malicious image through phishing emails, malicious websites, or file sharing platforms
3. When the victim opens, previews, or processes the image, the vulnerable ColorSync code parses the embedded ICC profile
4. The crafted profile triggers the memory corruption condition in the CMMNDimLinear::Interpolate function
5. The attacker gains arbitrary code execution with the privileges of the user running the application

Technical details regarding the uninitialized memory vulnerability can be found in the Packet Storm Exploit Report.

Detection Methods for CVE-2021-30917

Indicators of Compromise

• Unusual crashes or instability in applications processing image files, particularly those involving color profile handling
• Unexpected process spawning or network connections following image file preview or opening operations
• Suspicious ColorSync or image processing errors in system logs
• Anomalous memory access patterns in processes handling ICC profile data

Detection Strategies

• Monitor for suspicious image files with abnormally large or malformed ICC profile chunks using file integrity tools
• Implement endpoint detection rules to flag unexpected code execution following image preview operations
• Deploy behavioral analysis to detect processes exhibiting memory corruption exploitation patterns
• Configure application-level logging to capture ColorSync framework errors and anomalies

Monitoring Recommendations

• Enable detailed crash reporting on Apple devices to identify potential exploitation attempts
• Monitor system logs for ColorSync-related errors or crashes in /var/log/system.log on macOS
• Implement network monitoring to detect exfiltration following potential compromise via malicious images
• Review process execution chains for suspicious activity triggered by image preview applications

How to Mitigate CVE-2021-30917

Immediate Actions Required

• Update all affected Apple devices to the patched versions immediately
• Implement email gateway filtering to scan and quarantine potentially malicious image attachments
• Educate users about the risks of opening image files from untrusted sources
• Consider temporarily disabling automatic image preview features until patches are applied

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Organizations should apply the following updates:

• iOS/iPadOS: Update to iOS 15.1, iPadOS 15.1, or iOS 14.8.1/iPadOS 14.8.1 - See Apple Security Advisory HT212867
• macOS Monterey: Update to version 12.0.1 - See Apple Security Advisory HT212869
• macOS Big Sur: Update to version 11.6.1 - See Apple Security Advisory HT212872
• macOS Catalina: Apply Security Update 2021-007 - See Apple Security Advisory HT212871
• tvOS: Update to version 15.1 - See Apple Security Advisory HT212876
• watchOS: Update to version 8.1 - See Apple Security Advisory HT212874

Workarounds

• Avoid opening image files from untrusted sources until patches can be applied
• Configure email clients to disable automatic image rendering and preview functionality
• Use sandboxed or isolated environments when handling images from unknown sources
• Implement strict application control policies to limit which applications can process image files

# Check current macOS version to verify patch status
sw_vers -productVersion

# Check for available software updates on macOS
softwareupdate --list

# Install all available updates
softwareupdate --install --all