CVE-2015-8964 in Android
Summary
by MITRE
The tty_set_termios_ldisc function in drivers/tty/tty_ldisc.c in the Linux kernel before 4.5 allows local users to obtain sensitive information from kernel memory by reading a tty data structure.
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Analysis
by VulDB Data Team • 09/30/2022
The vulnerability identified as CVE-2015-8964 resides within the Linux kernel's terminal line discipline implementation, specifically in the tty_set_termios_ldisc function located in drivers/tty/tty_ldisc.c. This flaw represents a classic information disclosure vulnerability that affects Linux kernel versions prior to 4.5, creating a significant security risk for systems relying on terminal I/O operations. The vulnerability manifests when local users can exploit improper memory handling within the tty subsystem, allowing them to access kernel memory contents that should remain protected from user-space access.
The technical root cause of this vulnerability stems from inadequate validation and memory management within the terminal line discipline framework. When the tty_set_termios_ldisc function processes terminal settings, it fails to properly sanitize or validate the data structure operations, creating a pathway for unauthorized memory reads. This occurs because the function does not adequately protect kernel memory regions that contain sensitive information, including potentially confidential data structures, session information, or other privileged data that should remain isolated from user-space processes. The vulnerability specifically affects the tty data structure handling, where the lack of proper bounds checking and memory access controls enables attackers to extract kernel memory contents through carefully crafted read operations.
The operational impact of CVE-2015-8964 is substantial for local attackers who can leverage this vulnerability to gain unauthorized access to kernel memory. This information disclosure can potentially reveal sensitive system information including process credentials, memory layouts, cryptographic keys, or other confidential data that could aid in further exploitation attempts. The vulnerability is particularly concerning because it operates at the kernel level, where the extracted information could provide attackers with insights into system internals, memory organization, and potentially enable more sophisticated attacks such as privilege escalation or information gathering for targeted exploitation. The local nature of this vulnerability means that any user with access to a terminal session could potentially exploit this flaw, making it a significant concern for multi-user systems.
This vulnerability maps to CWE-200 (Information Exposure) and aligns with ATT&CK techniques related to information gathering and privilege escalation. The flaw demonstrates poor input validation and memory safety practices that are commonly addressed through proper kernel memory management and access control mechanisms. Organizations should implement immediate mitigation strategies including kernel updates to version 4.5 or later, which contain the necessary patches to address the improper memory handling in the tty subsystem. Additional mitigations may include restricting local user access where possible, implementing proper access controls for terminal sessions, and monitoring for unusual memory access patterns that could indicate exploitation attempts. The vulnerability also underscores the importance of regular kernel security updates and proper security testing of core system components to prevent similar issues from arising in other subsystems.