CVE-2021-30907 in macOS
Summary
by MITRE • 08/25/2021
An integer overflow was addressed through improved input validation. This issue is fixed in iOS 15.1 and iPadOS 15.1, macOS Monterey 12.0.1, iOS 14.8.1 and iPadOS 14.8.1, tvOS 15.1, watchOS 8.1, Security Update 2021-007 Catalina, macOS Big Sur 11.6.1. A malicious application may be able to elevate privileges.
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Analysis
by VulDB Data Team • 10/31/2021
The vulnerability identified as CVE-2021-30907 represents a critical integer overflow flaw that exists within Apple's operating systems, specifically affecting iOS, iPadOS, macOS, tvOS, and watchOS platforms. This type of vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which occurs when an integer value exceeds its maximum representable limit and wraps around to a smaller value. The flaw manifests in the operating system's handling of input validation processes, creating a potential pathway for malicious actors to exploit the system's privilege escalation mechanisms. The vulnerability was addressed through enhanced input validation measures that prevent the integer overflow condition from being triggered during normal system operations.
The technical nature of this vulnerability allows a malicious application to potentially elevate privileges within the operating system environment. When an integer overflow occurs in system-level code, it can lead to unpredictable behavior that attackers may exploit to gain unauthorized access to elevated system functions. This particular flaw demonstrates how seemingly minor input validation gaps can create significant security risks, as the overflow can cause memory corruption or unexpected control flow behavior that malicious code can manipulate. The exploitation of such vulnerabilities typically requires sophisticated attack vectors that leverage the overflow condition to execute arbitrary code with higher privileges than normally permitted.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it represents a potential gateway for more extensive system compromise. Attackers who successfully exploit this integer overflow could potentially gain root access to affected devices, allowing them to modify system files, install persistent malware, or access sensitive user data. The widespread nature of the affected platforms means that the potential attack surface is extensive, covering mobile devices, tablets, desktop computers, and wearable technology. This vulnerability aligns with ATT&CK technique T1068 which involves exploiting vulnerabilities to gain elevated privileges, and T1548.001 which covers abuse of system privileges through privilege escalation.
Apple's response to this vulnerability included releasing security updates across multiple operating system versions, with fixes appearing in iOS 15.1, iPadOS 15.1, macOS Monterey 12.0.1, iOS 14.8.1, iPadOS 14.8.1, tvOS 15.1, watchOS 8.1, and various macOS security updates. The remediation approach focused on strengthening input validation mechanisms to prevent the integer overflow condition from occurring in the first place. Organizations and users should prioritize applying these security updates immediately, as the vulnerability could be actively exploited in the wild. The fix represents a defensive programming approach that prevents the overflow by validating input sizes and ranges before processing them in integer arithmetic operations. This vulnerability highlights the importance of robust input validation and proper handling of integer operations in system-level software, as such flaws can have cascading effects on overall system security.