CVE-2015-3643 in usb-creator
Summary
by MITRE
usb-creator before 0.2.38.3ubuntu0.1 on Ubuntu 12.04 LTS, before 0.2.56.3ubuntu0.1 on Ubuntu 14.04 LTS, before 0.2.62ubuntu0.3 on Ubuntu 14.10, and before 0.2.67ubuntu0.1 on Ubuntu 15.04 allows local users to gain privileges by leveraging a missing call check_polkit for the KVMTest method.
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2015-3643 affects the usb-creator utility across multiple Ubuntu LTS versions, representing a critical privilege escalation flaw that undermines system security through inadequate access control mechanisms. This vulnerability specifically targets the KVMTest method within the usb-creator component, which is responsible for creating bootable USB drives and managing virtual machine configurations. The flaw manifests when the application fails to properly validate user permissions through the check_polkit function, creating a dangerous gap in the authorization framework that malicious local users can exploit to elevate their privileges.
The technical implementation of this vulnerability stems from a missing security check within the KVMTest method execution path. The usb-creator utility relies on PolicyKit (polkit) for authorization decisions, but the specific method fails to invoke the check_polkit function before proceeding with operations that require elevated privileges. This omission creates an exploitable condition where local attackers can bypass normal access controls and execute privileged operations without proper authentication. The flaw is particularly dangerous because it allows unprivileged users to perform actions typically restricted to root or administrative accounts, effectively breaking down the fundamental security boundaries that protect system integrity.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the capability to execute arbitrary code with root privileges on affected systems. Attackers can leverage this flaw to modify system files, install malicious software, or establish persistent backdoors within the target environment. The vulnerability affects multiple Ubuntu releases including 12.04 LTS, 14.04 LTS, 14.10, and 15.04, indicating a widespread exposure across the Ubuntu ecosystem. Given that usb-creator is commonly used for system administration tasks and USB drive creation, this vulnerability represents a significant threat to desktop and server environments where local access is possible.
The security implications align with CWE-284, which addresses improper access control vulnerabilities, and can be mapped to ATT&CK technique T1068, which covers local privilege escalation through system binary manipulation. This vulnerability demonstrates how seemingly routine system utilities can contain critical security flaws that compromise entire systems when proper authorization checks are omitted. The affected versions represent a substantial portion of the Ubuntu user base, making this vulnerability particularly dangerous from a threat perspective. Organizations running these vulnerable versions face significant risk of unauthorized system compromise, especially in environments where local user access is not strictly controlled. Remediation requires immediate patching of the usb-creator package to ensure proper PolicyKit integration and validation of all privileged operations. The vulnerability underscores the importance of comprehensive security testing for system utilities and the critical need for proper access control implementation in all components that handle privileged operations.