CVE-2018-17336 in udisks
Summary
by MITRE
UDisks 2.8.0 has a format string vulnerability in udisks_log in udiskslogging.c, allowing attackers to obtain sensitive information (stack contents), cause a denial of service (memory corruption), or possibly have unspecified other impact via a malformed filesystem label, as demonstrated by %d or %n substrings.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability identified as CVE-2018-17336 represents a critical format string flaw within UDisks 2.8.0, specifically in the udisks_log function located in udiskslogging.c. This issue arises from improper handling of user-supplied input when processing filesystem labels, creating a pathway for malicious actors to exploit the system through carefully crafted malformed labels containing format specifiers such as %d or %n. The vulnerability falls under the category of CWE-134, which specifically addresses the use of format strings with user-supplied data without proper validation or sanitization.
The technical implementation of this vulnerability allows attackers to manipulate the format string processing logic by injecting malicious format specifiers into filesystem labels. When the udisks_log function processes these malformed labels, it directly passes the user-controlled input to printf-style functions without adequate sanitization. This creates multiple attack vectors including information disclosure through stack content exposure, potential memory corruption leading to denial of service conditions, and in some cases could enable more sophisticated attacks depending on the execution environment. The use of %n format specifiers particularly poses a risk for writing arbitrary values to memory locations, while %d and other format specifiers can reveal stack contents and potentially lead to information leakage.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can be leveraged to cause system instability through memory corruption. Attackers can craft specific filesystem labels that, when processed by UDisks, trigger the format string vulnerability and potentially lead to application crashes or system hangs. The vulnerability is particularly concerning in environments where UDisks is used for automated or unattended operations, as it could be exploited to create persistent denial of service conditions. Additionally, the information disclosure aspect could reveal sensitive stack contents that might aid in more advanced exploitation techniques or help attackers understand the memory layout of the affected system.
Mitigation strategies for CVE-2018-17336 should focus on immediate patching of UDisks to version 2.8.1 or later, which contains the necessary fixes for the format string vulnerability. System administrators should also implement input validation measures to sanitize filesystem labels before they are processed by UDisks, particularly when dealing with untrusted user input. The implementation of proper format string handling practices, including the use of printf format specifiers with explicit string arguments rather than direct user input, should be enforced throughout the codebase. Security monitoring should be enhanced to detect unusual patterns in filesystem label processing that might indicate exploitation attempts. Organizations should also consider implementing privilege separation and access controls to limit the potential impact of successful exploitation, aligning with ATT&CK technique T1068 which addresses local privilege escalation and system compromise through vulnerable system components. The vulnerability demonstrates the importance of proper input validation and secure coding practices, particularly when dealing with logging functions and user-supplied data in system-level utilities.