CVE-2009-0158 in Mac OS X
Summary
by MITRE
Stack-based buffer overflow in telnet in Apple Mac OS X 10.4.11 and 10.5 before 10.5.7 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a long hostname for a telnet server.
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Analysis
by VulDB Data Team • 05/27/2025
The vulnerability described in CVE-2009-0158 represents a critical stack-based buffer overflow affecting the telnet service implementation in Apple Mac OS X versions 10.4.11 and 10.5 prior to 10.5.7. This flaw resides within the telnet server component that handles hostname resolution and connection establishment processes, creating a pathway for remote exploitation that can result in arbitrary code execution or system crash. The vulnerability manifests when the telnet service receives a malformed hostname parameter that exceeds the allocated buffer space on the stack, leading to memory corruption that can be leveraged by malicious actors to gain unauthorized system access or disrupt service availability.
The technical implementation of this vulnerability stems from inadequate input validation within the telnet server's hostname processing routines. When a client connects to a telnet server and provides a hostname parameter that exceeds the predetermined buffer limits, the application fails to properly enforce bounds checking, allowing the overflow to occur. This stack-based buffer overflow directly violates the principles of secure programming and aligns with CWE-121, which specifically addresses stack-based buffer overflow conditions. The flaw operates at the application layer of the network stack, making it accessible through standard telnet connections without requiring special privileges or authentication, thus presenting a significant attack surface for remote adversaries.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass full system compromise capabilities. Remote attackers can exploit the buffer overflow to inject malicious code into the telnet server process, potentially gaining elevated privileges or executing arbitrary commands with the privileges of the telnet service account. This represents a critical security risk for systems that maintain telnet services, particularly in enterprise environments where legacy applications may still rely on telnet protocols for remote access. The vulnerability also enables denial of service attacks that can crash the telnet service and potentially the entire system, disrupting legitimate user access and network operations.
Mitigation strategies for CVE-2009-0158 should prioritize immediate system updates and patches provided by Apple to address the specific buffer overflow conditions in the telnet implementation. Organizations should disable telnet services where possible and implement network segmentation to limit access to systems running vulnerable telnet implementations. Security monitoring should include detection of unusual hostname lengths and malformed connection attempts that may indicate exploitation attempts. The vulnerability demonstrates the importance of input validation and bounds checking as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1210 for exploiting buffer overflows to gain system access. Additionally, implementing network-based intrusion detection systems can help identify and block malicious telnet connection attempts that target this specific vulnerability. System administrators should also consider migrating to more secure remote access protocols such as SSH that do not suffer from similar buffer overflow vulnerabilities, thereby reducing the attack surface and improving overall system security posture.