CVE-2017-12989 in macOS
Summary
by MITRE
The RESP parser in tcpdump before 4.9.2 could enter an infinite loop due to a bug in print-resp.c:resp_get_length().
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Analysis
by VulDB Data Team • 09/06/2024
The vulnerability identified as CVE-2017-12989 represents a critical flaw in the tcpdump network packet analysis tool that affects versions prior to 4.9.2. This issue resides within the Redis Serialization Protocol (RESP) parser implementation, specifically in the print-resp.c module where the resp_get_length() function contains a fundamental parsing error. The vulnerability manifests when tcpdump encounters specially crafted RESP protocol data during network traffic analysis, leading to a denial of service condition that can severely impact network monitoring and security operations.
The technical root cause of this vulnerability stems from an insufficient boundary check within the RESP parser's length extraction mechanism. When processing RESP protocol data structures, the resp_get_length() function fails to properly validate input boundaries, allowing malformed or maliciously constructed RESP messages to cause the parser to enter an infinite loop. This occurs because the function does not adequately handle cases where the length field in RESP protocol messages contains invalid or unexpected values that cause the parsing logic to continuously iterate without making progress toward parsing completion. The flaw directly maps to CWE-835, which specifically addresses the issue of loops that do not make progress toward completion, creating a potential denial of service condition.
From an operational perspective, this vulnerability poses significant risks to network security infrastructure that relies on tcpdump for traffic analysis and monitoring. Security operations centers and network administrators using affected versions of tcpdump may experience complete service disruption when analyzing network traffic containing maliciously crafted RESP protocol data. The infinite loop condition effectively renders the tcpdump process unresponsive, preventing further packet analysis and potentially masking other security threats during the period when the tool is hung. This vulnerability is particularly concerning in environments where tcpdump is used for real-time network monitoring, intrusion detection, or forensic analysis, as it can completely disable critical security tools without any indication of the underlying issue.
The impact of this vulnerability extends beyond simple denial of service to potentially compromise network security operations and incident response capabilities. Attackers could exploit this weakness by crafting network traffic containing malformed RESP protocol data, causing network monitoring tools to become unresponsive and potentially disrupting security operations. This aligns with ATT&CK technique T1498, which covers network denial of service attacks, as the vulnerability enables an attacker to cause a persistent disruption of network monitoring capabilities. Organizations relying on tcpdump for security operations may find their ability to detect and respond to network threats severely compromised, as the tool becomes unusable during active attacks.
Mitigation strategies for this vulnerability require immediate upgrade to tcpdump version 4.9.2 or later, which contains the patched RESP parser implementation that properly handles boundary conditions and prevents the infinite loop condition. Network administrators should also implement additional monitoring to detect when tcpdump processes become unresponsive and establish automated restart procedures for monitoring services. Security teams should consider implementing network segmentation and traffic filtering rules to prevent exposure to malformed RESP protocol data, while also conducting thorough testing of upgraded tcpdump versions to ensure no regression issues affect existing network monitoring workflows. The fix addresses the core parsing logic by implementing proper input validation and boundary checks that prevent the parser from entering infinite loops when encountering unexpected RESP protocol structures.