CVE-2016-0758 in Android
Summary
by MITRE • 01/25/2023
Integer overflow in lib/asn1_decoder.c in the Linux kernel before 4.6 allows local users to gain privileges via crafted ASN.1 data.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2016-0758 represents a critical integer overflow flaw within the Linux kernel's ASN.1 decoder component located in lib/asn1_decoder.c. This vulnerability affects Linux kernel versions prior to 4.6 and poses a significant security risk by enabling local attackers to escalate their privileges through carefully crafted ASN.1 data structures. The issue stems from improper handling of integer arithmetic during the decoding process, where the kernel fails to properly validate or constrain integer values that could potentially overflow and corrupt memory structures. This type of vulnerability falls under the Common Weakness Enumeration category CWE-190, which specifically addresses integer overflow conditions that can lead to unpredictable behavior and potential privilege escalation. The vulnerability is particularly dangerous because it operates within the kernel space where malicious code execution can directly compromise system integrity and potentially provide attackers with root-level access to affected systems.
The technical exploitation of this vulnerability occurs when a local user submits maliciously formatted ASN.1 data to the kernel's decoder functions. During the decoding process, the kernel performs arithmetic operations on integer values that represent data structure sizes or element counts. When these operations exceed the maximum representable value for the integer type being used, an integer overflow occurs. This overflow can result in unexpected behavior where calculated buffer sizes become negative or excessively large, leading to memory corruption that attackers can manipulate to execute arbitrary code with kernel privileges. The attack vector is particularly insidious because it requires no network access or external interaction - only local user access to the system. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1068, which involves the exploitation of legitimate system tools and processes to gain elevated privileges, and T1055, which encompasses process injection and memory manipulation techniques that can be leveraged through kernel-level flaws.
The operational impact of CVE-2016-0758 extends beyond simple privilege escalation to potentially compromise entire system security postures. Systems running vulnerable kernel versions become susceptible to local privilege escalation attacks that could allow attackers to gain root access, modify critical system files, install persistent backdoors, or exfiltrate sensitive data. The vulnerability affects a wide range of Linux distributions that have not yet updated to kernel version 4.6 or later, including enterprise servers, desktop systems, and embedded devices that rely on older kernel versions. Organizations using affected systems face significant risk exposure, particularly in environments where local user access is not strictly controlled or where users have legitimate administrative access that could be exploited. The vulnerability's impact is amplified by the fact that it operates at the kernel level, making detection and mitigation more challenging compared to user-space vulnerabilities. Security teams must implement immediate patching strategies, monitor system logs for signs of exploitation attempts, and consider implementing additional access controls and privilege separation measures to reduce the attack surface. The vulnerability also highlights the importance of thorough code review and testing for integer arithmetic operations in kernel space, particularly in cryptographic and data parsing components that handle untrusted input from various sources including network protocols and file formats.
Mitigation strategies for CVE-2016-0758 primarily focus on immediate kernel updates to version 4.6 or later, which contain the necessary patches to address the integer overflow condition in the ASN.1 decoder. System administrators should prioritize patch deployment across all affected systems, particularly those handling sensitive data or operating in high-risk environments. Additional defensive measures include implementing strict access controls to limit local user privileges where possible, monitoring for unusual system behavior that might indicate exploitation attempts, and maintaining up-to-date security information through vulnerability databases and security advisories. Organizations should also consider implementing kernel module signing and secure boot mechanisms to prevent unauthorized kernel modifications that could potentially exploit this vulnerability or similar flaws. The vulnerability serves as a reminder of the critical importance of maintaining current kernel versions and implementing comprehensive security practices that include regular vulnerability assessments, code review processes, and proactive security monitoring to identify and address potential security weaknesses before they can be exploited by malicious actors.