CVE-2017-13764 in Wireshark
Summary
by MITRE
In Wireshark 2.4.0, the Modbus dissector could crash with a NULL pointer dereference. This was addressed in epan/dissectors/packet-mbtcp.c by adding length validation.
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Analysis
by VulDB Data Team • 12/27/2022
The vulnerability identified as CVE-2017-13764 represents a critical NULL pointer dereference flaw within Wireshark's Modbus dissector component. This issue affected Wireshark version 2.4.0 and stemmed from inadequate input validation within the packet-mbtcp.c file that handles Modbus TCP protocol decoding. The Modbus protocol operates as a master-slave communication protocol commonly used in industrial control systems and SCADA networks, making this vulnerability particularly concerning for operational technology environments. When processing malformed or specially crafted Modbus packets, the dissector would attempt to dereference a null pointer, leading to an application crash that could potentially disrupt network monitoring operations.
The technical implementation of this vulnerability resides in the packet-mbtcp.c file where the Modbus TCP dissector fails to properly validate packet lengths before attempting to access memory structures. This type of flaw falls under CWE-476 which specifically addresses NULL pointer dereference conditions, and represents a classic example of insufficient input validation that can lead to denial of service attacks. The vulnerability exploits the lack of proper boundary checking when parsing Modbus TCP headers, particularly in scenarios where packet length fields contain invalid or unexpected values. Attackers could craft malicious packets that would trigger this condition during packet capture and analysis, causing Wireshark to terminate unexpectedly.
The operational impact of this vulnerability extends beyond simple application instability, as it could be leveraged in targeted denial of service attacks against network monitoring infrastructure. In industrial environments where Wireshark is commonly used for network analysis and troubleshooting, such a crash could interrupt critical monitoring operations and potentially mask malicious activities. The vulnerability demonstrates the importance of robust input validation in network protocol analyzers, as these tools often process untrusted data from network traffic. Network administrators and security analysts who rely on Wireshark for network visibility could face operational disruptions when encountering specially crafted Modbus traffic, particularly in environments where industrial protocols are monitored alongside standard network traffic.
The remediation implemented by the Wireshark development team involved adding explicit length validation checks within the packet-mbtcp.c file to ensure that packet structures contain valid length information before attempting to process them. This fix aligns with defensive programming practices recommended by the ATT&CK framework for network monitoring tools, specifically addressing the need for robust input validation in protocol parsing components. The solution demonstrates the importance of validating all input data, particularly in network analysis tools that must handle diverse and potentially malicious traffic patterns. Organizations should ensure their Wireshark installations are updated to versions containing this fix, as the vulnerability could be exploited in targeted attacks against network monitoring systems. The remediation also highlights the broader security principle that protocol dissectors must be resilient to malformed inputs, as these components often serve as critical infrastructure for network security operations and should not be susceptible to crashes that could impact network visibility and monitoring capabilities.