Apple WebKit Memory Corruption Remote Code Execution Vulnerability (CVE-2023-42917) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTApple iOS prior to 17.1.2, iPadOS prior to 17.1.2, macOS Sonoma prior to 14.1.2, and Safari prior to 17.1.2
Processing maliciously crafted web content may lead to arbitrary code execution, with active exploitation reported in the wild
Immediately apply the official Apple software updates to upgrade operating systems and Safari to the patched versions
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to upgrade the operating system and Safari to the latest patched versions. Use the following commands to update macOS systems via the command line.
# Check for available updates and install all security patches on macOS
sudo softwareupdate -l
sudo softwareupdate -i -a2. Temporary Workaround & Hardening Configuration
For high-risk environments where immediate patching is not feasible, enable 'Lockdown Mode' to reduce the attack surface by disabling complex WebKit features such as JIT compilation.
# Verify if Lockdown Mode or specific MDM profiles are active on macOS
system_profiler SPConfigurationProfileDataType | grep -i 'LockdownMode'3. Log Audit & IoC Verification Commands
Run the following script on macOS endpoints to audit the current OS and Safari versions to identify vulnerable assets.
#!/bin/bash
# Audit script for macOS and Safari version verification
echo '[+] Checking macOS Version...'
sw_vers
echo '[+] Checking Safari Version...'
if [ -d '/Applications/Safari.app' ]; then
defaults read /Applications/Safari.app/Contents/Info.plist BundleShortVersionString
else
echo '[-] Safari installation not found in default directory.'
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2023-42917) is a critical memory corruption issue residing within Apple's WebKit rendering engine. The root cause stems from inadequate locking mechanisms during concurrent resource access in multi-threaded operations. This synchronization failure leads to a race condition, resulting in an out-of-bounds write or memory corruption (CWE-787). Apple resolved this issue by implementing improved locking mechanisms to ensure thread-safe memory operations.
2. Exploitation Mechanics & Attack Scenario
An attacker exploits this vulnerability by hosting a specially crafted web page containing malicious WebKit-compatible payloads. When a target user visits the malicious website or opens an application that utilizes the vulnerable WebKit framework, the rendering engine processes the malicious web content. The lack of proper locking triggers memory corruption, allowing the attacker to bypass memory protections, hijack the execution flow, and execute arbitrary code within the context of the application sandbox.
3. Infrastructure & Business Impact
As a CISA KEV-listed vulnerability, this flaw has been actively exploited in targeted attacks, specifically targeting iOS versions prior to iOS 16.7.1. In an enterprise environment, successful exploitation on employee devices (Macs, iPhones, iPads) can lead to complete device compromise, credential theft, and lateral movement within corporate networks, posing a severe threat to business continuity and data confidentiality.
Official Vendor Advisories & References
A memory corruption vulnerability was addressed with improved locking. This issue is fixed in iOS 17.1.2 and iPadOS 17.1.2, macOS Sonoma 14.1.2, Safari 17.1.2. Processing web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been exploited against versions of iOS before iOS 16.7.1.
Frequently Asked SecOps Questions (CVE-2023-42917)
FAQQ1. How critical is CVE-2023-42917 and is it actively exploited in the wild?
CVE-2023-42917 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 9.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2023-42917?
Primary impacted vendors include apple across safari, iphone_os, ipados, macos. Scope summary: Apple iOS and iPadOS versions prior to 17.1.2, macOS Sonoma versions prior to 14.1.2, and Safari versions prior to 17.1.2 (Active exploitation reported on versions prior to iOS 16.7.1)
Q3. What temporary mitigations or workarounds exist for CVE-2023-42917 before patching?
[Mitigation] Immediately apply the official Apple software updates to upgrade operating systems and Safari to the patched versions Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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