CVE-2017-12893 in macOS
Summary
by MITRE
The SMB/CIFS parser in tcpdump before 4.9.2 has a buffer over-read in smbutil.c:name_len().
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-12893 represents a critical buffer over-read flaw within the tcpdump network packet analysis tool's Server Message Block/Common Internet File System parsing functionality. This issue specifically affects versions of tcpdump prior to 4.9.2 and resides within the smbutil.c source file at the name_len() function implementation. The vulnerability occurs when tcpdump processes network traffic containing SMB/CIFS protocol packets, creating a scenario where the parser reads beyond the allocated memory boundaries while attempting to calculate the length of names within SMB protocol structures. This type of flaw falls under the category of memory safety issues and can be classified as a CWE-125 vulnerability, which represents an out-of-bounds read condition that allows attackers to access memory locations beyond the intended buffer boundaries. The issue demonstrates a classic example of how protocol parsers can become attack vectors when proper input validation and boundary checking mechanisms are absent or insufficient.
The technical exploitation of this vulnerability requires an attacker to craft and transmit specially malformed SMB/CIFS packets to a system running an affected version of tcpdump in promiscuous mode or when capturing network traffic that includes such packets. When tcpdump processes these malicious packets, the name_len() function fails to properly validate the length of name fields within SMB protocol structures, leading to memory over-read conditions that could potentially expose sensitive data from adjacent memory locations. The attack vector is particularly concerning because it can be executed remotely through network traffic capture without requiring direct system compromise or authentication. The vulnerability impacts the integrity and confidentiality of network monitoring operations, as the over-read could potentially reveal memory contents including stack data, heap information, or other sensitive system information that might aid in further exploitation attempts.
The operational impact of CVE-2017-12893 extends beyond simple data exposure, as it can potentially enable more sophisticated attacks through information disclosure that might reveal memory layout details or other sensitive information. Network administrators and security professionals who rely on tcpdump for network monitoring and analysis are at risk of having their monitoring systems compromised, as the vulnerability can lead to data leakage during packet analysis operations. This vulnerability aligns with ATT&CK technique T1046 which involves network service scanning, and T1059 which involves command and scripting interpreters, as the compromised monitoring capabilities could provide attackers with additional reconnaissance information. The vulnerability also represents a significant concern for environments where tcpdump is used for security monitoring, incident response, or network forensics, as the integrity of the captured data could be compromised. Organizations using affected versions of tcpdump in production environments should consider the potential for data leakage during normal network monitoring operations.
The recommended mitigation strategy for CVE-2017-12893 involves immediate upgrading to tcpdump version 4.9.2 or later, which contains the necessary patches to address the buffer over-read condition in the SMB/CIFS parser. System administrators should also consider implementing network segmentation and access controls to limit exposure to potentially malicious network traffic that could trigger the vulnerability. Additionally, monitoring for unusual network traffic patterns or unexpected tcpdump behavior could serve as an early detection mechanism. Organizations should also review their network monitoring tool configurations to ensure that only necessary traffic is being captured and analyzed, reducing the attack surface for such vulnerabilities. The fix implemented in tcpdump 4.9.2 addresses the core issue by adding proper bounds checking to the name_len() function and ensuring that all name field lengths are properly validated before memory access operations occur, thereby preventing the buffer over-read condition that could lead to information disclosure or system instability.