CVE-2023-32435: Apple Safari RCE Vulnerability

CVE-2023-32435 Overview

CVE-2023-32435 is a memory corruption vulnerability in Apple WebKit that was addressed with improved state management. This vulnerability affects multiple Apple products including Safari, macOS, iOS, and iPadOS. When a user processes maliciously crafted web content, an attacker can achieve arbitrary code execution on the target system. Apple has confirmed that this issue has been actively exploited in the wild against devices running iOS versions prior to iOS 15.7.

Critical Impact

This vulnerability enables remote attackers to execute arbitrary code through malicious web content, with confirmed active exploitation in the wild. The vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating significant risk to organizations.

Affected Products

• Apple Safari (versions prior to 16.4)
• Apple macOS Ventura (versions prior to 13.3)
• Apple iOS and iPadOS (versions prior to 16.4 and 15.7.7)

Discovery Timeline

• 2023-06-23 - CVE-2023-32435 published to NVD
• 2025-10-23 - Last updated in NVD database

Technical Details for CVE-2023-32435

Vulnerability Analysis

CVE-2023-32435 is classified as CWE-787 (Out-of-Bounds Write), a memory corruption vulnerability that occurs when WebKit improperly manages state during web content processing. The flaw allows attackers to corrupt memory in a way that can be leveraged for arbitrary code execution. This type of vulnerability in a browser engine is particularly dangerous because it can be triggered simply by visiting a malicious website or viewing compromised web content, requiring no additional user interaction beyond navigating to the attacker-controlled page.

The vulnerability's network-based attack vector means exploitation can occur remotely. While user interaction is required (visiting a malicious page), the barrier to exploitation is low once the user engages with the content. Successful exploitation grants the attacker code execution in the context of the affected application, potentially compromising confidentiality, integrity, and availability of the system.

Root Cause

The root cause of this vulnerability lies in improper state management within WebKit's web content processing engine. When handling certain web content, WebKit failed to properly maintain and validate memory state, leading to memory corruption. This state management issue creates conditions where memory can be written outside of intended boundaries, enabling attackers to manipulate program execution flow.

Attack Vector

The attack is executed remotely via specially crafted web content. An attacker can host malicious content on a compromised or attacker-controlled website, deliver the payload through phishing emails containing links, or inject malicious content into legitimate websites through cross-site scripting or similar techniques. When a victim's browser processes this malicious content, the memory corruption occurs, allowing the attacker to execute arbitrary code on the target device.

Given the confirmed active exploitation against older iOS versions, attackers have demonstrated the ability to weaponize this vulnerability in real-world scenarios, likely as part of targeted attacks or sophisticated threat campaigns.

Detection Methods for CVE-2023-32435

Indicators of Compromise

• Unexpected Safari or WebKit crashes followed by suspicious process behavior
• Network connections to unknown or suspicious domains immediately following web browsing activity
• Presence of unexpected processes spawned by WebKit-related components
• Anomalous memory allocation patterns in WebKit processes

Detection Strategies

• Monitor for unusual WebKit process behavior including unexpected child process creation or network activity
• Implement network traffic analysis to detect connections to known malicious infrastructure associated with exploitation campaigns
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation techniques
• Review system logs for Safari or WebKit crash reports that may indicate exploitation attempts

Monitoring Recommendations

• Enable crash reporting and analyze WebKit-related crashes for patterns consistent with exploitation
• Monitor for privilege escalation attempts following web browser activity
• Implement browser isolation solutions to contain potential exploitation attempts
• Track software versions across the organization to identify unpatched systems

How to Mitigate CVE-2023-32435

Immediate Actions Required

• Update all Apple devices to the patched versions immediately: macOS Ventura 13.3, Safari 16.4, iOS 16.4/iPadOS 16.4, or iOS 15.7.7/iPadOS 15.7.7
• Prioritize patching devices running iOS versions prior to 15.7, as these were specifically targeted in active exploitation
• Implement network-level protections to block known malicious domains associated with exploitation
• Consider deploying web content filtering to reduce exposure to potentially malicious websites

Patch Information

Apple has released security updates addressing this vulnerability across multiple products. Organizations should apply the following updates:

• macOS Ventura 13.3 - See Apple Support Advisory HT213670
• Safari 16.4 - See Apple Support Advisory HT213671
• iOS 16.4 and iPadOS 16.4 - See Apple Support Advisory HT213676
• iOS 15.7.7 and iPadOS 15.7.7 - See Apple Support Advisory HT213811

This vulnerability is tracked in the CISA Known Exploited Vulnerabilities Catalog, and federal agencies are required to remediate it according to the specified timeline.

Workarounds

• Limit web browsing on unpatched devices to trusted, known-safe websites only
• Use alternative browsers that do not rely on WebKit on macOS systems where possible
• Implement strict web content filtering at the network perimeter
• Consider using managed browser configurations that restrict JavaScript execution or other dynamic content on untrusted sites
• Employ network segmentation to limit the impact of potential device compromise

# Verify iOS/iPadOS version on device
# Settings > General > About > Software Version
# Ensure version is 16.4+ or 15.7.7+

# Verify macOS version
sw_vers -productVersion
# Ensure version is 13.3 or later for Ventura

# Verify Safari version on macOS
/Applications/Safari.app/Contents/MacOS/Safari --version
# Ensure version is 16.4 or later