CVE-2008-1215 in OpenBSD
Summary
by MITRE
Stack-based buffer overflow in the command_Expand_Interpret function in command.c in ppp (aka user-ppp), as distributed in FreeBSD 6.3 and 7.0, OpenBSD 4.1 and 4.2, and the net/userppp package for NetBSD, allows local users to gain privileges via long commands containing "~" characters.
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability identified as CVE-2008-1215 represents a critical stack-based buffer overflow flaw within the ppp package implementation across multiple operating systems. This issue affects FreeBSD versions 6.3 and 7.0, OpenBSD versions 4.1 and 4.2, and the net/userppp package for NetBSD, demonstrating the widespread nature of this security weakness. The vulnerability specifically resides in the command_Expand_Interpret function located within the command.c source file, which handles command processing within the ppp daemon context. The flaw manifests when the system processes commands containing tilde characters, creating an exploitable condition that can be leveraged by local attackers to escalate privileges.
The technical exploitation mechanism involves the manipulation of command strings that contain tilde characters, which triggers an improper buffer boundary check during command interpretation. When the command_Expand_Interpret function processes these specially crafted inputs, it fails to properly validate the length of the input string against the allocated buffer space, resulting in a classic stack-based buffer overflow condition. This overflow allows attackers to overwrite adjacent stack memory locations, potentially corrupting return addresses and control flow information. The vulnerability's classification aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions where insufficient bounds checking permits data to overwrite adjacent memory locations. The attack vector requires local system access, as the vulnerability is not remotely exploitable but can be leveraged by users with existing system access to elevate their privileges to root level.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with a pathway to gain complete system control through local user accounts. The exploitation process typically involves crafting a malicious command string containing an excessive number of tilde characters that exceed the buffer capacity, causing the overflow to overwrite critical program state information. This vulnerability directly maps to ATT&CK technique T1068, which covers the exploitation of local privilege escalation vulnerabilities, and T1548.001, covering abuse of system privileges. The affected systems become vulnerable to unauthorized privilege escalation attacks, potentially allowing attackers to execute arbitrary code with elevated privileges, modify system files, establish persistent access mechanisms, and compromise the confidentiality, integrity, and availability of the affected systems. The widespread distribution of this vulnerability across multiple operating system families indicates that organizations using these platforms face significant risk exposure, particularly in environments where local user access is not properly restricted.
Mitigation strategies for CVE-2008-1215 should prioritize immediate patch application from the respective operating system vendors, as the vulnerability affects core networking components that are essential to system functionality. System administrators must implement comprehensive access controls to limit local user privileges and monitor for unusual command execution patterns that might indicate exploitation attempts. The implementation of input validation mechanisms within the ppp package would prevent the overflow condition by properly bounds-checking command strings before processing. Additionally, deploying intrusion detection systems capable of identifying suspicious command sequences containing excessive tilde characters can provide early warning of potential exploitation attempts. Organizations should also consider implementing privilege separation mechanisms and regular security audits to identify and remediate similar vulnerabilities in other system components. The remediation approach should include not only applying vendor patches but also conducting thorough vulnerability assessments of similar buffer handling functions within the system to identify potential analogous weaknesses that might require similar mitigation strategies.