CVE-2016-6504 in Wireshark
Summary
by MITRE
epan/dissectors/packet-ncp2222.inc in the NDS dissector in Wireshark 1.12.x before 1.12.13 does not properly maintain a ptvc data structure, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted packet.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability identified as CVE-2016-6504 resides within the Network Discovery System (NDS) dissector component of Wireshark, specifically in the packet-ncp2222.inc file that handles NCP2222 protocol analysis. This flaw affects Wireshark versions 1.12.x prior to 1.12.13, representing a critical denial of service vulnerability that can be exploited remotely by attackers who craft malicious network packets. The vulnerability manifests when the dissector fails to properly maintain a ptvc (packet type value cache) data structure during packet processing, creating a scenario where the application encounters a NULL pointer dereference condition.
The technical implementation of this vulnerability stems from improper handling of packet data structures within the dissector's parsing logic. When Wireshark processes a specially crafted NCP2222 packet, the dissector attempts to access memory locations that have not been properly initialized or validated, leading to a NULL pointer dereference. This memory access violation causes the Wireshark application to crash abruptly, resulting in a complete denial of service condition for the network analysis functionality. The ptvc data structure, which serves as a cache for packet type information, becomes corrupted or improperly managed during the parsing sequence, creating the conditions necessary for the NULL pointer dereference to occur.
From an operational perspective, this vulnerability presents significant risks to network security analysts and forensic investigators who rely on Wireshark for network traffic analysis. An attacker positioned on the same network segment or capable of injecting malicious packets can exploit this vulnerability to disrupt network monitoring operations, potentially causing analysts to lose critical network visibility during security incidents. The remote exploitation capability means that the vulnerability can be triggered without requiring physical access to the target system, making it particularly dangerous in environments where network monitoring tools are deployed. The denial of service impact extends beyond simple application crashes, as it can compromise the integrity of ongoing network investigations and potentially mask malicious network activity.
The vulnerability aligns with CWE-476, which identifies NULL pointer dereference as a common weakness in software applications. This classification reflects the fundamental programming error where a program attempts to access memory through a pointer that has not been properly initialized to point to valid memory locations. From an adversarial perspective, this vulnerability can be categorized under ATT&CK technique T1499.002, which involves network denial of service attacks, specifically focusing on application or system exploitation to disrupt network operations. The exploitability of this vulnerability is enhanced by the fact that it requires no special privileges or authentication, making it accessible to attackers with basic network access.
Mitigation strategies for CVE-2016-6504 primarily involve upgrading to Wireshark version 1.12.13 or later, which contains the necessary patches to properly maintain the ptvc data structure during packet processing. Network administrators should implement regular patch management procedures to ensure all instances of Wireshark are updated with the latest security fixes. Additional protective measures include implementing network segmentation to limit exposure, deploying network monitoring solutions that can detect and alert on unusual packet patterns, and establishing incident response procedures to address potential exploitation attempts. Organizations should also consider implementing network access controls to prevent unauthorized packet injection and maintain comprehensive network traffic logs for forensic analysis in case of successful exploitation attempts.