CVE-2023-42883: Apple Safari DOS Vulnerability

CVE-2023-42883 Overview

CVE-2023-42883 is a memory handling vulnerability affecting multiple Apple products including Safari, macOS, iOS, iPadOS, watchOS, and tvOS. The vulnerability exists in the image processing functionality where improper memory handling can lead to a denial-of-service condition when processing a specially crafted image. This issue affects a broad range of Apple's ecosystem, requiring user interaction to trigger the vulnerability through malicious image content.

Critical Impact

Processing a malicious image can cause a denial-of-service condition, potentially crashing applications or rendering devices temporarily unusable across the Apple ecosystem including mobile devices, desktops, and wearables.

Affected Products

• Apple Safari (versions prior to 17.2)
• Apple macOS Sonoma (versions prior to 14.2)
• Apple iOS 17 and iPadOS 17 (versions prior to 17.2)
• Apple iOS 16 and iPadOS 16 (versions prior to 16.7.3)
• Apple watchOS (versions prior to 10.2)
• Apple tvOS (versions prior to 17.2)
• Debian Linux 11.0 and 12.0 (via WebKitGTK)

Discovery Timeline

• December 12, 2023 - CVE-2023-42883 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-42883

Vulnerability Analysis

This vulnerability resides in the image processing components shared across Apple's operating systems and Safari browser. The flaw stems from insufficient memory handling during image parsing operations. When a user opens or previews a maliciously crafted image file, the vulnerable code path fails to properly manage memory allocations, leading to resource exhaustion or an unhandled exception that crashes the application or system component.

The local attack vector requires user interaction, meaning an attacker must convince a victim to open or preview a malicious image. This could occur through various social engineering techniques such as embedding malicious images in documents, emails, web pages, or messaging applications. While the vulnerability does not lead to code execution or data exfiltration, the denial-of-service impact can disrupt user workflows and potentially affect availability of critical applications.

Root Cause

The root cause of CVE-2023-42883 lies in improper memory handling within Apple's image processing framework. When parsing certain image formats, the code fails to properly validate memory boundaries or handle edge cases in image metadata. This leads to memory corruption or excessive allocation that the system cannot recover from gracefully, resulting in application or component crashes.

Attack Vector

The attack requires local access with user interaction. An attacker must craft a malicious image file and deliver it to the victim through various means:

1. Email attachments - Malicious images sent as attachments that trigger processing when previewed
2. Web content - Images embedded in web pages that Safari automatically attempts to render
3. Messaging applications - Images shared through iMessage or other messaging platforms
4. Document embedding - Malicious images embedded within documents that trigger preview functionality

When the victim opens or previews the malicious image, the vulnerable memory handling code is triggered, causing the denial-of-service condition. The vulnerability does not compromise data confidentiality or integrity but severely impacts availability.

Detection Methods for CVE-2023-42883

Indicators of Compromise

• Repeated crashes of Safari, Preview, or other image-handling applications
• System logs showing memory-related exceptions in image processing components
• Unexpected application terminations when opening image files from untrusted sources
• Kernel panics or system instability following image file access

Detection Strategies

• Monitor application crash reports for patterns involving image processing components
• Implement endpoint detection rules to identify repeated application crashes tied to specific file access
• Configure SentinelOne to alert on anomalous process termination patterns in Safari and system image handlers
• Review crash logs for memory exhaustion or corruption signatures in WebKit-related processes

Monitoring Recommendations

• Enable verbose logging for Safari and image processing subsystems on macOS
• Deploy file inspection policies to scan incoming images from external sources
• Configure alerting for unusual application restart patterns on iOS devices via MDM solutions
• Monitor network traffic for image files originating from suspicious or untrusted domains

How to Mitigate CVE-2023-42883

Immediate Actions Required

• Update all Apple devices to the latest patched versions immediately
• Advise users to avoid opening image files from untrusted sources until patching is complete
• Consider temporarily disabling automatic image preview features in email clients
• Deploy enterprise MDM policies to enforce software updates across the organization

Patch Information

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

• Safari 17.2 - Apple Support Article HT214034
• macOS Sonoma 14.2 - Apple Support Article HT214036
• iOS 17.2 and iPadOS 17.2 - Apple Support Article HT214035
• iOS 16.7.3 and iPadOS 16.7.3 - Apple Support Article HT214034
• watchOS 10.2 - Apple Support Article HT214041
• tvOS 17.2 - Apple Support Article HT214040

For Debian Linux users, refer to Debian Security Advisory DSA-5580 for WebKitGTK updates.

Workarounds

• Disable automatic image loading in Safari via Preferences > Advanced settings
• Configure email clients to not automatically download or display image attachments
• Use alternative browsers temporarily until Safari can be updated
• Implement network-level filtering to block known malicious image hosting domains

# Verify Safari version on macOS
/Applications/Safari.app/Contents/MacOS/Safari --version

# Check macOS version
sw_vers -productVersion

# Force software update check on macOS
softwareupdate --list

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