CVE-2016-2522 in Wireshark
Summary
by MITRE
The dissect_ber_constrained_bitstring function in epan/dissectors/packet-ber.c in the ASN.1 BER dissector in Wireshark 2.0.x before 2.0.2 does not verify that a certain length is nonzero, which allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted packet.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability described in CVE-2016-2522 affects the ASN.1 Basic Encoding Rules dissector within Wireshark version 2.0.x before 2.0.2. This issue resides in the dissect_ber_constrained_bitstring function located in epan/dissectors/packet-ber.c, which is responsible for parsing and interpreting ASN.1 bit string encodings in network traffic. The flaw represents a classic buffer over-read condition that occurs when processing malformed ASN.1 BER encoded packets, specifically those containing constrained bit strings with invalid length parameters.
The technical implementation of this vulnerability stems from insufficient input validation within the dissector's parsing logic. When the dissect_ber_constrained_bitstring function processes a bit string element, it fails to properly validate that the length field contains a non-zero value before attempting to read from the associated data buffer. This oversight creates a scenario where an attacker can craft a malicious packet containing an ASN.1 bit string with a zero-length field, causing the dissector to attempt reading beyond the bounds of allocated memory. The absence of proper bounds checking allows the application to access memory locations that are either uninitialized or not part of the intended data structure, leading to unpredictable behavior.
The operational impact of this vulnerability is significant as it enables remote attackers to execute a denial of service attack against Wireshark installations. When a victim processes a specially crafted packet containing the malformed ASN.1 bit string, the dissector crashes due to the out-of-bounds memory read, resulting in a complete application crash. This vulnerability can be exploited in scenarios where Wireshark is used to analyze network traffic from untrusted sources, such as during network forensics, security auditing, or when analyzing traffic from potentially malicious networks. The attack requires no special privileges or authentication, making it particularly dangerous as it can be triggered by simply opening a malicious capture file or processing network traffic containing the crafted packet.
This vulnerability maps to CWE-129, which describes improper validation of array index or iterator values, and specifically relates to improper bounds checking in the context of packet analysis. The attack vector aligns with ATT&CK technique T1059.007, which involves the execution of code through network traffic analysis tools, and T1499.004, which covers network denial of service attacks targeting network monitoring tools. The flaw demonstrates a critical weakness in the validation mechanisms of network protocol dissectors, which are essential components for network analysis and security monitoring.
The recommended mitigation strategy involves upgrading to Wireshark version 2.0.2 or later, which contains the necessary patches to address the bounds checking issue. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious traffic, while ensuring that network analysis tools are regularly updated with the latest security patches. Additionally, administrators should consider implementing network monitoring solutions that can detect and block malformed packets before they reach systems running Wireshark, and maintain comprehensive backup procedures to quickly recover from potential service disruptions caused by such vulnerabilities.