CVE-2006-6397 in FreeBSD
Summary
by MITRE
** DISPUTED ** Integer overflow in banner/banner.c in FreeBSD, NetBSD, and OpenBSD might allow local users to modify memory via a long banner. NOTE: CVE and multiple third parties dispute this issue. Since banner is not setuid, an exploit would not cross privilege boundaries in normal operations. This issue is not a vulnerability.
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Analysis
by VulDB Data Team • 08/08/2024
The vulnerability described in CVE-2006-6397 relates to an integer overflow condition found in the banner utility across multiple open source operating systems including FreeBSD, NetBSD, and OpenBSD. This issue was initially reported as potentially allowing local users to modify memory through manipulation of banner length parameters, but subsequent analysis has led to significant disputes regarding its actual vulnerability status. The banner utility serves as a system information display tool that typically shows system identification details to users during login processes or system initialization. The integer overflow occurs within the banner/banner.c source file where the program fails to properly validate or handle excessively long banner strings, potentially leading to buffer manipulation scenarios.
From a technical perspective, the integer overflow represents a classic software flaw where an application attempts to store a value that exceeds the maximum capacity of the data type being used for storage. This particular vulnerability manifests in the banner utility's handling of banner length parameters, where the program processes user-supplied or system-generated banner text without adequate bounds checking. When a maliciously long banner string is provided, the integer arithmetic operations involved in calculating buffer sizes can overflow, causing unpredictable behavior in memory management. The potential for memory corruption arises from the improper handling of integer values that should be constrained to prevent buffer overflows, which falls under the CWE-190 category of Integer Overflow or Wraparound.
The operational impact of this vulnerability, while disputed by multiple parties including the official CVE database, presents a complex scenario for security practitioners to evaluate. The primary consideration is that the banner utility is not setuid, meaning it does not run with elevated privileges and cannot directly escalate user permissions. This characteristic significantly limits the attack surface and potential damage scope, as local users would be constrained to their current privilege level when exploiting this condition. However, the disputed nature of this vulnerability means that security professionals must carefully assess whether the reported conditions can actually be exploited in real-world scenarios, particularly given that the utility operates within normal user privilege boundaries. The ATT&CK framework would classify this as a potential technique for privilege escalation or code execution, but the lack of setuid permissions makes such exploitation highly constrained.
The disputed status of this vulnerability reflects the complexity often found in security assessments where initial reports may not fully account for the operational context and privilege boundaries of affected software components. Security researchers and vendors have expressed concerns about the validity of the original vulnerability claims, particularly regarding whether the integer overflow can actually result in memory corruption that crosses privilege boundaries. This case demonstrates the importance of thorough validation and testing before classifying security issues as actual vulnerabilities. Organizations should consider the broader context of their system configurations and the specific usage patterns of the banner utility when evaluating this reported issue. The lack of setuid permissions means that even if the integer overflow could theoretically occur, it would not provide a direct path for privilege escalation, making the overall risk assessment more nuanced and context-dependent.