CVE-2023-41983: Apple Safari DOS Vulnerability

CVE-2023-41983 Overview

CVE-2023-41983 is a memory handling vulnerability affecting Apple's WebKit browser engine used in Safari and other Apple products. The vulnerability exists in how WebKit processes web content, which can lead to improper memory handling operations. When a user visits a maliciously crafted website, the vulnerability can be exploited to cause a denial-of-service condition, rendering the browser or device unresponsive.

Critical Impact

Processing malicious web content can cause denial-of-service, affecting availability of Apple Safari, iOS, iPadOS, and macOS devices.

Affected Products

• Apple Safari (versions prior to 17.1)
• Apple iOS and iPadOS (versions prior to 16.7.2 and 17.1)
• Apple macOS (versions prior to Sonoma 14.1)
• Fedora Project Fedora 37, 38, and 39
• Debian Linux 11.0 and 12.0

Discovery Timeline

• October 25, 2023 - CVE-2023-41983 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-41983

Vulnerability Analysis

This vulnerability stems from improper memory handling within Apple's WebKit rendering engine. WebKit is the core browser engine that powers Safari and is also used by applications across iOS, iPadOS, and macOS that display web content. The flaw is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating that the vulnerability involves memory operations that exceed intended boundaries.

When WebKit processes specially crafted web content, the engine fails to properly manage memory operations, leading to conditions that can exhaust system resources or corrupt memory state. This results in a denial-of-service condition where the browser or affected application becomes unresponsive, potentially requiring a restart to recover normal functionality.

The vulnerability requires user interaction—specifically, a user must navigate to or be redirected to a malicious web page containing the exploit payload. No authentication or elevated privileges are required to trigger the vulnerability, making it accessible to any attacker who can convince a victim to visit a malicious URL.

Root Cause

The root cause of CVE-2023-41983 lies in improper memory handling within WebKit's content processing routines. The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating that memory operations during web content parsing do not properly validate or restrict access within allocated memory bounds. This can lead to memory corruption or resource exhaustion when processing maliciously crafted web content.

Attack Vector

The attack vector for CVE-2023-41983 is network-based, requiring user interaction. An attacker would need to craft a malicious webpage containing content designed to trigger the memory handling flaw in WebKit. The attack scenario typically involves:

1. The attacker hosts malicious web content on a server they control or compromises a legitimate website
2. The victim navigates to the malicious page through phishing, malvertising, or social engineering
3. WebKit processes the malicious content, triggering improper memory handling
4. The browser or application experiences denial-of-service, becoming unresponsive

The vulnerability does not require any special permissions or authentication, and the impact is limited to availability (denial-of-service) without evidence of data confidentiality or integrity compromise.

Detection Methods for CVE-2023-41983

Indicators of Compromise

• Unexpected browser crashes or hangs when visiting specific websites
• Safari or WebKit-based applications becoming unresponsive during web content rendering
• System logs indicating WebKit process crashes with memory-related errors
• Elevated memory usage by browser processes before becoming unresponsive

Detection Strategies

• Monitor endpoint logs for repeated Safari or WebKit process crashes
• Implement web proxy logging to identify access to known malicious domains delivering exploit content
• Deploy browser-based detection rules that identify anomalous memory consumption patterns
• Review system crash reports for WebKit-related memory handling exceptions

Monitoring Recommendations

• Enable detailed logging for browser crashes and memory exceptions on managed endpoints
• Configure SIEM alerting for patterns of repeated browser restarts across multiple endpoints
• Monitor network traffic for connections to recently registered or low-reputation domains
• Implement user behavior analytics to detect unusual browsing patterns associated with exploitation attempts

How to Mitigate CVE-2023-41983

Immediate Actions Required

• Update Safari to version 17.1 or later immediately
• Update iOS and iPadOS devices to version 16.7.2, 17.1, or later
• Update macOS to Sonoma 14.1 or later
• For Fedora and Debian Linux systems, apply the latest WebKitGTK security updates
• Restrict access to untrusted websites through web filtering solutions

Patch Information

Apple has released security updates addressing CVE-2023-41983 across multiple products. Administrators should apply the following updates:

• macOS Sonoma 14.1: Apple Security Update HT213984
• Safari 17.1: Apple Security Update HT213986
• iOS 16.7.2 and iPadOS 16.7.2: Apple Security Update HT213981
• iOS 17.1 and iPadOS 17.1: Apple Security Update HT213982

For Linux distributions, refer to Debian Security Advisory DSA-5557 and the respective Fedora Package Announcements for WebKitGTK updates.

Workarounds

• Implement web content filtering to block access to untrusted or low-reputation websites
• Use alternative browsers that do not rely on WebKit for critical browsing activities
• Enable strict content security policies on enterprise web applications
• Deploy endpoint detection and response (EDR) solutions to monitor for exploitation attempts

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

# Verify macOS version
sw_vers -productVersion

# Check iOS/iPadOS version via MDM or device settings
# Settings > General > About > Software Version