CVE-2017-13055 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:isis_print_is_reach_subtlv().
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Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-13055 represents a critical buffer over-read flaw within the ISO IS-IS protocol parser of tcpdump software version 4.9.1 and earlier. This issue resides in the print-isoclns.c source file at the isis_print_is_reach_subtlv() function, where improper input validation leads to memory access violations. The IS-IS protocol, or Intermediate System to Intermediate System, is a routing protocol used in large network environments to facilitate communication between network devices. When tcpdump processes network traffic containing IS-IS protocol data, it attempts to parse the protocol structure to provide meaningful output to users. However, the flawed implementation fails to properly verify buffer boundaries during sub-TLV (Type-Length-Value) parsing operations.
The technical exploitation of this vulnerability occurs when tcpdump encounters malformed IS-IS protocol packets with oversized or malformed sub-TLV structures. During normal operation, the parser expects specific data formats and sizes for various protocol components. When presented with unexpected or maliciously crafted data, the parser continues reading beyond allocated memory boundaries, potentially accessing uninitialized memory regions or memory belonging to other processes. This over-read condition can result in information disclosure, application crashes, or potentially even arbitrary code execution depending on the specific memory access patterns and system configuration. The vulnerability falls under CWE-125, which specifically addresses "Out-of-bounds Read" conditions in software implementations, and represents a classic example of insufficient input validation within network protocol parsers.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios. Network administrators and security professionals who rely on tcpdump for network monitoring and analysis could experience system instability when processing traffic containing malicious IS-IS packets. This becomes particularly concerning in enterprise environments where IS-IS is commonly deployed for internal routing operations, as attackers could potentially exploit this vulnerability to disrupt network monitoring tools or gain unauthorized access to sensitive network information. The vulnerability affects systems where tcpdump is used for packet analysis, including security operations centers, network troubleshooting environments, and forensic analysis platforms. The ATT&CK framework categorizes this as a network protocol manipulation technique under the T1071.004 sub-technique for application layer protocol, where adversaries exploit parsing flaws to achieve unauthorized access or system compromise.
Mitigation strategies for CVE-2017-13055 involve immediate software updates to tcpdump version 4.9.2 or later, which includes proper bounds checking and input validation for IS-IS protocol parsing. System administrators should also implement network segmentation and access controls to limit exposure to potentially malicious traffic, while deploying intrusion detection systems that can identify malformed IS-IS packets. Additional defensive measures include configuring tcpdump with restricted permissions and monitoring for unusual memory access patterns in network analysis tools. The vulnerability serves as a reminder of the critical importance of input validation in network protocol implementations and highlights the need for regular security updates in network monitoring tools. Organizations should also consider implementing network traffic filtering rules that can prevent the propagation of malformed IS-IS packets through their network infrastructure, reducing the attack surface for such vulnerabilities.