CVE-2017-13026 in macOS
Summary
by MITRE
The ISO IS-IS parser in tcpdump before 4.9.2 has a buffer over-read in print-isoclns.c, several functions.
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Analysis
by VulDB Data Team • 09/08/2024
The vulnerability identified as CVE-2017-13026 represents a critical buffer over-read flaw within the ISO IS-IS protocol parser of tcpdump software versions prior to 4.9.2. This issue resides in the print-isoclns.c source file where multiple functions fail to properly validate input data lengths before processing ISO IS-IS (Intermediate System to Intermediate System) protocol packets. The IS-IS protocol is a link-state routing protocol widely used in large service provider networks and enterprise environments for dynamic routing of packets across networks. The buffer over-read condition occurs when tcpdump attempts to parse malformed or specially crafted IS-IS packets that exceed expected data boundaries, potentially leading to memory access violations and system instability.
The technical implementation of this vulnerability stems from inadequate bounds checking within the IS-IS packet parsing functions. When tcpdump encounters an IS-IS packet, it processes various subfields including area addresses, system identifiers, and protocol data units without sufficient validation of the incoming data length against allocated buffer sizes. This allows attackers to craft malicious packets that contain oversized data fields, causing the parser to read beyond the allocated memory boundaries. The flaw manifests as a classic buffer over-read condition where the program attempts to access memory locations that were not allocated for the current operation, potentially exposing sensitive data from adjacent memory regions or causing application crashes.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios to potentially enable information disclosure and arbitrary code execution under specific conditions. Network administrators who rely on tcpdump for network monitoring and troubleshooting face significant risks when running vulnerable versions of the software, as attackers could exploit this flaw to gain unauthorized access to system memory contents. The vulnerability affects environments where tcpdump is used to capture and analyze IS-IS traffic, which includes large enterprise networks, service provider infrastructures, and network security monitoring systems. According to CWE classification, this represents a CWE-125: Out-of-bounds Read vulnerability that falls under the broader category of memory safety issues.
Mitigation strategies for CVE-2017-13026 primarily focus on immediate software updates and network segmentation measures. Organizations should prioritize upgrading to tcpdump version 4.9.2 or later, which includes patches that implement proper bounds checking and input validation for IS-IS protocol parsing. Additionally, network administrators should consider implementing network access controls to limit exposure to potentially malicious IS-IS traffic, particularly in environments where IS-IS is not actively used. The ATT&CK framework categorizes this vulnerability under T1059.007: Command and Scripting Interpreter: PowerShell, as exploitation may involve crafting malicious network traffic to trigger the buffer over-read condition. Security teams should also implement network monitoring solutions that can detect and alert on unusual IS-IS packet patterns that might indicate exploitation attempts, while maintaining regular vulnerability assessments to identify other potential buffer over-read conditions in network analysis tools.