CVE-2016-0728 in Android
Summary
by MITRE • 01/25/2023
The join_session_keyring function in security/keys/process_keys.c in the Linux kernel before 4.4.1 mishandles object references in a certain error case, which allows local users to gain privileges or cause a denial of service (integer overflow and use-after-free) via crafted keyctl commands.
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Analysis
by VulDB Data Team • 07/08/2024
The vulnerability identified as CVE-2016-0728 resides within the Linux kernel's key management subsystem, specifically in the join_session_keyring function located in security/keys/process_keys.c. This flaw represents a critical security issue that affects Linux kernel versions prior to 4.4.1, where the kernel fails to properly manage object references during error handling scenarios. The vulnerability manifests when crafted keyctl commands are executed by local users, creating conditions that can be exploited to either escalate privileges or cause system instability through denial of service attacks.
The technical root cause of this vulnerability stems from improper reference counting and memory management within the kernel's keyring subsystem. When an error occurs during the join_session_keyring operation, the function does not correctly handle object reference management, leading to situations where kernel memory objects may be freed while still referenced elsewhere in the system. This creates a use-after-free condition that can be exploited by malicious local users to execute arbitrary code with elevated privileges or trigger integer overflow conditions that result in system crashes.
From a cybersecurity perspective, this vulnerability aligns with CWE-415 which describes improper handling of memory allocation and deallocation, and CWE-122 which addresses improper restriction of operations within a recognized security domain. The attack vector requires local user access but can result in privilege escalation to kernel level, making it particularly dangerous in multi-user environments where untrusted users might have access to system resources. The vulnerability operates at the kernel level and can be classified under ATT&CK technique T1068 which involves exploiting local system privileges.
The operational impact of CVE-2016-0728 extends beyond simple denial of service scenarios to include potential system compromise and privilege escalation. Local users who can execute keyctl commands can manipulate the kernel's keyring management system to create conditions where memory corruption occurs, potentially allowing attackers to execute code with root privileges. The integer overflow component of this vulnerability can cause unpredictable behavior in kernel memory management, leading to system instability and crashes that may be difficult to diagnose or recover from. Organizations running affected kernel versions face significant risk as this vulnerability can be exploited without requiring network access or special privileges beyond local system access.
Mitigation strategies for CVE-2016-0728 primarily involve upgrading to Linux kernel version 4.4.1 or later, which contains the necessary patches to address the improper reference handling in the join_session_keyring function. System administrators should also implement monitoring for unusual keyctl command usage patterns and consider restricting local user access to keyctl functionality where possible. Additional defensive measures include maintaining up-to-date kernel security patches, implementing kernel module signing policies, and conducting regular security assessments of kernel configurations. Organizations should also consider implementing intrusion detection systems that can monitor for suspicious kernel-level activities that might indicate exploitation attempts of this vulnerability.