CVE-2010-3350 in bareFTP
Summary
by MITRE
bareFTP 0.3.4 places a zero-length directory name in the LD_LIBRARY_PATH, which allows local users to gain privileges via a Trojan horse shared library in the current working directory.
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Analysis
by VulDB Data Team • 09/27/2021
The vulnerability identified as CVE-2010-3350 affects bareFTP version 0.3.4 and represents a classic privilege escalation flaw rooted in improper library path handling. This issue manifests when the application processes the LD_LIBRARY_PATH environment variable, which is used by the dynamic linker to locate shared libraries required for program execution. The specific flaw occurs when the application inadvertently includes a zero-length directory name within the LD_LIBRARY_PATH, creating a dangerous condition where the current working directory is implicitly included in the library search path. This behavior violates fundamental security principles and creates an exploitable condition that adversaries can leverage for privilege escalation.
The technical implementation of this vulnerability stems from the way bareFTP manages environment variables during execution, particularly how it processes and constructs the LD_LIBRARY_PATH. When a zero-length directory is present in the path, the dynamic linker interprets this as the current working directory, effectively allowing any shared library placed in the current directory to be loaded. This creates a Trojan horse scenario where an attacker can place a malicious shared library in the same directory as the vulnerable application, and when the application executes, it will load the attacker-controlled library instead of the legitimate system library. This behavior aligns with CWE-426, which addresses the insecure handling of environment variables and library loading mechanisms. The vulnerability operates under the principle that applications should not implicitly trust the current working directory for library loading, a concept that is fundamental to secure programming practices.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can be exploited in various attack scenarios depending on the target system and the privileges of the user running the vulnerable application. Local attackers who can write to the current working directory of the bareFTP process can effectively execute arbitrary code with the privileges of the target user, potentially escalating to root access if the application runs with elevated privileges. The attack vector is particularly concerning because it requires minimal prerequisites - an attacker only needs write access to the directory where the application is executed and knowledge of the application's execution context. This vulnerability can be exploited in automated attacks or during routine system maintenance activities where users might inadvertently place malicious libraries in directories where vulnerable applications execute. The implications are significant in multi-user environments where applications might be executed with different privilege levels, as the vulnerability can be leveraged to compromise the entire system's security posture.
Mitigation strategies for CVE-2010-3350 should focus on both immediate patching and defensive programming practices. The primary solution involves updating to a patched version of bareFTP that properly handles the LD_LIBRARY_PATH environment variable without introducing zero-length directory entries. System administrators should also implement proper file permissions and directory access controls to prevent unauthorized modifications to application directories. Additionally, implementing security measures such as setting the LD_LIBRARY_PATH explicitly to known safe directories, using secure library loading practices, and employing runtime monitoring can help detect and prevent exploitation attempts. This vulnerability demonstrates the importance of following secure coding practices and adheres to ATT&CK technique T1068, which covers privilege escalation through environment variable manipulation. Organizations should also consider implementing application whitelisting and monitoring for suspicious library loading activities to detect potential exploitation attempts before they succeed.