CVE-2016-4774 in tvOS
Summary
by MITRE
The kernel in Apple iOS before 10, OS X before 10.12, tvOS before 10, and watchOS before 3 allows attackers to obtain sensitive memory-layout information or cause a denial of service (out-of-bounds read) via a crafted app, a different vulnerability than CVE-2016-4773 and CVE-2016-4776.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2016-4774 represents a critical memory safety issue affecting Apple's operating systems including iOS versions prior to 10.0, OS X versions before 10.12, tvOS versions before 10.0, and watchOS versions before 3.0. This flaw resides within the kernel component of these operating systems, which serves as the core foundation responsible for system-level operations and memory management. The vulnerability manifests through out-of-bounds read conditions that can be triggered by specially crafted applications, potentially exposing sensitive memory layout information to attackers. This type of vulnerability falls under the category of memory corruption issues that can be exploited to gain unauthorized access to system information or disrupt normal operational functions.
The technical nature of this vulnerability involves improper bounds checking within kernel memory operations, allowing malicious applications to read memory locations beyond the intended boundaries of allocated buffers or data structures. When an attacker crafts a malicious application that triggers this condition, the system's kernel fails to properly validate memory access requests, enabling the unauthorized reading of adjacent memory regions. This can result in the disclosure of sensitive information such as kernel memory addresses, stack contents, or other confidential data that should remain protected from user-space applications. The vulnerability is particularly concerning because it operates at the kernel level, where privileged system operations occur, making it potentially exploitable for more severe attacks including privilege escalation or information disclosure.
From an operational impact perspective, this vulnerability creates significant security risks for affected Apple devices as it enables attackers to gather critical system information that could be used to facilitate more sophisticated attacks. The out-of-bounds read condition can potentially reveal memory layout details that are essential for bypassing security mechanisms like address space layout randomization, which is a common exploit mitigation technique. Additionally, the vulnerability can cause denial of service conditions by triggering system crashes or instability when malicious applications attempt to access invalid memory regions. This type of vulnerability aligns with CWE-129, which describes improper validation of array indices, and represents a classic example of how memory safety issues can compromise system integrity and availability.
The exploitation of CVE-2016-4774 demonstrates the importance of kernel-level security in modern operating systems and aligns with ATT&CK techniques related to privilege escalation and information gathering. Security researchers have noted that vulnerabilities of this nature often serve as stepping stones for more complex attacks, as the memory layout information obtained can be used to craft more precise exploits against other system components. The vulnerability also highlights the need for comprehensive input validation and bounds checking mechanisms within kernel code, particularly when handling data from untrusted sources such as user applications. Organizations and users affected by this vulnerability should prioritize immediate remediation through official Apple security updates and patches, as the potential for exploitation remains significant given the broad range of affected operating systems and devices. The incident underscores the critical importance of maintaining up-to-date security patches and the inherent risks associated with running outdated operating system versions that may contain unpatched kernel vulnerabilities.