CVE-2005-0351 in OpenServer
Summary
by MITRE
Buffer overflow in (1) termsh, (2) atcronsh, and (3) auditsh in SCO OpenServer 5.0.6 and 5.0.7 might allow local users to execute arbitrary code via a long HOME environment variable.
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Analysis
by VulDB Data Team • 07/06/2018
The vulnerability identified as CVE-2005-0351 represents a critical buffer overflow flaw affecting multiple shell components within SCO OpenServer versions 5.0.6 and 5.0.7. This issue impacts three distinct programs including termsh, atcronsh, and auditsh which are integral parts of the operating system's terminal and scheduling functionalities. The vulnerability stems from insufficient input validation when processing the HOME environment variable, creating an exploitable condition that could be leveraged by local attackers to gain elevated privileges. The buffer overflow occurs during the handling of environment variables, specifically when the system attempts to store or process an excessively long HOME variable value. This flaw falls under the CWE-121 category of stack-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack vector requires local system access, making it a local privilege escalation vulnerability that could potentially allow malicious users to execute arbitrary code with the privileges of the targeted processes. The affected programs termsh, atcronsh, and auditsh all share a common codebase vulnerability that fails to properly validate the length of the HOME environment variable before processing it. When a local user sets an overly long HOME variable, the programs attempt to copy this value into a fixed-size buffer without proper bounds checking, leading to memory corruption that can be exploited to overwrite return addresses and control program execution flow. The operational impact of this vulnerability extends beyond simple code execution, as successful exploitation could lead to complete system compromise, allowing attackers to bypass security controls and escalate privileges to root level access. This vulnerability directly relates to the ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and demonstrates how buffer overflow conditions can be weaponized to achieve unauthorized system access. The affected SCO OpenServer versions represent a legacy operating system environment where such vulnerabilities are particularly concerning due to limited security updates and the potential for long-term exposure in production environments. Organizations running these systems face significant risk as the vulnerability can be exploited by any local user with basic system access, making it a serious concern for system administrators who must consider the broader security implications of legacy operating systems. The vulnerability also highlights the importance of proper input validation and memory management practices in system-level software development, as the flaw exists in core system components rather than isolated applications. Security researchers have documented similar patterns in other Unix-like systems where environment variable handling has led to buffer overflow conditions, emphasizing the need for robust defensive programming practices. The exploitation of this vulnerability requires minimal prerequisites, making it particularly dangerous as it can be triggered through simple environment variable manipulation without requiring complex attack vectors. System administrators should prioritize patching these vulnerable components or implementing immediate mitigations to prevent potential exploitation, as the vulnerability represents a clear pathway for local privilege escalation that could compromise entire system operations.
The technical implementation of this buffer overflow vulnerability demonstrates how environment variables can serve as attack vectors when not properly validated. The HOME environment variable is commonly used by Unix-like systems to determine user home directory locations, and when processed by these shell programs without adequate bounds checking, it creates exploitable memory conditions. The specific programs affected share common code structures that fail to implement proper string length validation before copying environment variable values into fixed-size buffers. This pattern of vulnerability is consistent with many historical buffer overflow issues found in system utilities and shell components where legacy code does not account for potential input length variations. The vulnerability's classification as a local privilege escalation issue means that attackers do not require network access or complex attack chains, making it particularly dangerous in environments where local access is possible. From a security perspective, this vulnerability underscores the importance of the principle of least privilege and proper input validation in system-level code. The fact that this affects multiple components within the same operating system version suggests a systemic code quality issue that may extend to other similar programs within the SCO OpenServer ecosystem. The vulnerability also demonstrates how seemingly benign environment variables can become attack vectors when combined with poor defensive programming practices, highlighting the need for comprehensive security testing of system utilities and core components. Organizations should implement immediate mitigations such as restricting environment variable manipulation or applying available patches to prevent exploitation of this vulnerability. The ATT&CK framework categorizes this as a privilege escalation technique that leverages memory corruption vulnerabilities, making it a significant concern for system security teams responsible for protecting legacy operating environments. The vulnerability's exploitation potential makes it a high-priority issue for security assessments of SCO OpenServer installations, particularly those that may be exposed to untrusted local users or have inadequate access controls in place.