CVE-2017-6964 in dmcrypt-get-device
Summary
by MITRE
dmcrypt-get-device, as shipped in the eject package of Debian and Ubuntu, does not check the return value of the (1) setuid or (2) setgid function, which might cause dmcrypt-get-device to execute code, which was intended to run as an unprivileged user, as root. This affects eject through 2.1.5+deb1+cvs20081104-13.1 on Debian, eject before 2.1.5+deb1+cvs20081104-13.1ubuntu0.16.10.1 on Ubuntu 16.10, eject before 2.1.5+deb1+cvs20081104-13.1ubuntu0.16.04.1 on Ubuntu 16.04 LTS, eject before 2.1.5+deb1+cvs20081104-13.1ubuntu0.14.04.1 on Ubuntu 14.04 LTS, and eject before 2.1.5+deb1+cvs20081104-9ubuntu0.1 on Ubuntu 12.04 LTS.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability described in CVE-2017-6964 resides within the dmcrypt-get-device utility that is part of the eject package distributed with Debian and Ubuntu operating systems. This utility serves a critical role in managing removable media devices, particularly those encrypted with dm-crypt, which is a Linux kernel feature for transparent encryption of block devices. The flaw manifests in the improper handling of privilege management functions within the program's execution flow, creating a potential privilege escalation vector that could allow attackers to execute code with root privileges.
The technical root cause of this vulnerability stems from the failure of the dmcrypt-get-device utility to properly validate the return values of setuid and setgid function calls. These system calls are fundamental to Unix-like operating systems for changing process user and group identifiers, enabling programs to temporarily elevate their privileges to perform administrative tasks. When these functions fail to return successfully, the program should abort execution or handle the error appropriately, but in this case, the program continues execution with elevated privileges despite the failed privilege transition. This behavior violates the principle of least privilege and creates a scenario where unprivileged user code can potentially be executed with root permissions, representing a classic privilege escalation flaw.
The operational impact of this vulnerability extends across multiple Ubuntu and Debian releases, affecting systems from Ubuntu 12.04 LTS through Ubuntu 16.10, as well as the corresponding Debian versions. Attackers exploiting this vulnerability could potentially gain root access to systems running affected versions, enabling them to execute arbitrary code with the highest system privileges. This creates a significant security risk for any system that relies on the eject package for managing removable media, particularly in enterprise environments where such systems may be accessible to untrusted users. The vulnerability's presence in long-term support releases like Ubuntu 14.04 and 16.04 LTS makes it particularly concerning as these systems are often deployed in production environments where maintaining security patches can be challenging.
From a cybersecurity perspective, this vulnerability aligns with CWE-252, which describes an "Unchecked Return Value" condition where a program fails to check the result of a function call that might indicate failure. The flaw also maps to ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" by demonstrating how an attacker can leverage a programmatic weakness to gain elevated system privileges. The vulnerability's exploitation pathway follows the pattern of privilege escalation through improper access control mechanisms, where the failure to properly validate system call results creates an unexpected execution context that bypasses normal security boundaries. Organizations should implement immediate mitigations including updating to patched versions of the eject package, applying security patches, and monitoring for any suspicious root-level processes that might indicate exploitation attempts. System administrators should also consider implementing additional security controls such as mandatory access controls or privilege separation mechanisms to reduce the impact if such vulnerabilities are exploited in the future.