CVE-2024-27876: Apple iPadOS Race Condition Vulnerability

CVE-2024-27876 Overview

CVE-2024-27876 is a race condition vulnerability in Apple's archive extraction functionality across multiple operating systems including macOS, iOS, iPadOS, and visionOS. The vulnerability exists due to improper locking mechanisms during archive unpacking operations. When a user unpacks a maliciously crafted archive, an attacker can exploit the race condition to write arbitrary files to the system, potentially overwriting critical files or placing malicious content in sensitive locations.

Critical Impact

Unpacking a maliciously crafted archive may allow an attacker to write arbitrary files to the filesystem, potentially leading to code execution, privilege escalation, or system compromise.

Affected Products

• Apple macOS (versions prior to macOS Ventura 13.7, macOS Sonoma 14.7, and macOS Sequoia 15)
• Apple iOS and iPadOS (versions prior to iOS 17.7, iPadOS 17.7, iOS 18, and iPadOS 18)
• Apple visionOS (versions prior to visionOS 2)

Discovery Timeline

• September 17, 2024 - CVE-2024-27876 published to NVD
• November 4, 2025 - Last updated in NVD database

Technical Details for CVE-2024-27876

Vulnerability Analysis

This vulnerability (CWE-362) stems from a race condition in the archive extraction process on Apple platforms. Race conditions occur when the outcome of a process depends on the timing or sequence of uncontrollable events, and when proper synchronization mechanisms are not in place. In this case, the archive unpacking functionality lacks adequate locking during file write operations, creating a window where an attacker can manipulate the extraction process.

The vulnerability requires local access and user interaction—specifically, the victim must unpack a maliciously crafted archive file. While this limits automated exploitation, social engineering attacks distributing malicious archives via email, messaging apps, or downloads remain a significant threat vector. The integrity impact is high, as successful exploitation allows arbitrary file writes without affecting confidentiality or availability directly.

Root Cause

The root cause is insufficient synchronization in the archive extraction code path. When processing archive contents, the system performs file operations without proper locking mechanisms to ensure atomicity. This creates a Time-of-Check Time-of-Use (TOCTOU) window where the attacker can race against the extraction process to redirect file writes or modify extraction paths during the operation.

Apple addressed this by implementing improved locking mechanisms to ensure that file operations during archive extraction are properly synchronized and cannot be interrupted or manipulated by concurrent processes.

Attack Vector

The attack vector is local, requiring user interaction to unpack a maliciously crafted archive. The exploitation scenario involves:

1. An attacker crafts a malicious archive file specifically designed to trigger the race condition
2. The victim downloads or receives the malicious archive through any delivery mechanism (email attachment, web download, file sharing)
3. When the victim extracts the archive using the system's built-in extraction functionality, the race condition is triggered
4. The attacker's exploit code wins the race, allowing arbitrary file writes to attacker-controlled locations

This could enable an attacker to overwrite system configuration files, place executable code in startup locations, or modify application binaries. The arbitrary file write primitive is particularly dangerous as it can serve as a stepping stone to code execution or privilege escalation.

Detection Methods for CVE-2024-27876

Indicators of Compromise

• Unexpected file modifications in system directories following archive extraction operations
• Presence of unfamiliar or suspicious archive files (ZIP, TAR, etc.) in download folders or temporary directories
• Modified timestamps on critical system files that coincide with archive extraction activities
• Process crashes or unusual behavior during archive unpacking operations

Detection Strategies

• Monitor file system activities during archive extraction for anomalous write patterns to unexpected locations
• Implement endpoint detection rules to flag archive files being extracted with concurrent suspicious file operations
• Deploy behavioral analysis to detect TOCTOU attack patterns during file extraction workflows
• Audit logs for rapid sequences of file check and file write operations that may indicate race condition exploitation

Monitoring Recommendations

• Enable enhanced file system auditing on macOS and iOS endpoints to track file creation and modification events
• Monitor for archive extraction processes that result in writes outside expected destination directories
• Configure SentinelOne agents to alert on suspicious archive handling behavior and unexpected file system modifications
• Track downloaded archive files and correlate with subsequent file write events in sensitive locations

How to Mitigate CVE-2024-27876

Immediate Actions Required

• Update all Apple devices to the latest patched versions: macOS Ventura 13.7+, macOS Sonoma 14.7+, macOS Sequoia 15+, iOS 17.7+, iPadOS 17.7+, or iOS/iPadOS 18+, and visionOS 2+
• Warn users about the risks of extracting archives from untrusted sources until patches are applied
• Review and restrict archive extraction capabilities on critical systems where immediate patching is not possible
• Implement email gateway filtering to quarantine or scan archive attachments before delivery

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Detailed patch information is available in the official Apple Security Advisories:

• Apple Support Article #121234 - macOS Sequoia 15
• Apple Support Article #121238 - macOS Sonoma 14.7
• Apple Support Article #121246 - macOS Ventura 13.7
• Apple Support Article #121247 - iOS 18 and iPadOS 18
• Apple Support Article #121249 - iOS 17.7 and iPadOS 17.7
• Apple Support Article #121250 - visionOS 2

Additional technical details were disclosed in the Full Disclosure mailing list announcements from September 2024.

Workarounds

• Avoid extracting archive files from untrusted or unknown sources until patches can be applied
• Use alternative third-party archive extraction tools that may not be affected by this specific vulnerability
• Implement strict download policies and user training regarding archive file handling
• Consider application-level sandboxing or containerization for archive extraction operations on sensitive systems

# Verify macOS version to ensure patch is applied
sw_vers

# Check for available software updates
softwareupdate --list

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