CVE-2018-7331 in Wireshark
Summary
by MITRE
In Wireshark 2.4.0 to 2.4.4 and 2.2.0 to 2.2.12, epan/dissectors/packet-ber.c had an infinite loop that was addressed by validating a length.
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2018-7331 represents a critical denial of service flaw discovered in Wireshark network protocol analyzer versions ranging from 2.4.0 through 2.4.4 and 2.2.0 through 2.2.12. This issue resides within the packet-ber.c dissector module responsible for decoding Basic Encoding Rules (BER) data structures commonly used in telecommunications protocols including X.25, X.212, and various ASN.1-based applications. The flaw manifests as an infinite loop condition that occurs when processing malformed BER-encoded packets, specifically when the dissector fails to properly validate the length field of BER structures before attempting to process their contents.
The technical root cause of this vulnerability stems from inadequate input validation within the BER dissector implementation. When Wireshark encounters a packet containing BER-encoded data with an invalid or malformed length field, the parsing logic enters an infinite loop where it continuously processes the same data segment without advancing the parsing pointer. This condition is particularly dangerous because BER encoding allows for multiple representations of the same value including indefinite length forms, and the vulnerable code fails to properly handle these edge cases. The absence of proper bounds checking and length validation creates a scenario where an attacker can craft malicious packets that cause the Wireshark application to consume excessive CPU resources and eventually become unresponsive.
From an operational impact perspective, this vulnerability presents significant risks to network security operations and monitoring activities. When an attacker successfully exploits this flaw, they can cause Wireshark to enter an infinite loop, effectively rendering the network monitoring tool unusable for the duration of the attack. This denial of service condition can occur during routine network traffic analysis, packet capture sessions, or when processing network traffic from compromised systems. The vulnerability affects any user who processes network traffic containing crafted BER-encoded data, making it particularly concerning for security analysts, network administrators, and forensic investigators who rely on Wireshark for network traffic analysis. The infinite loop condition typically results in high CPU utilization and can cause the application to become unresponsive, requiring manual intervention to terminate the process and restart the application.
The vulnerability aligns with CWE-835, which specifically addresses the issue of infinite loops in software implementations, and demonstrates how improper input validation can lead to denial of service conditions. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain where an adversary first gains access to network traffic and then uses this flaw to disrupt network monitoring capabilities, potentially allowing further malicious activity to go undetected. The remediation for this vulnerability involved implementing proper length validation checks within the BER dissector module to ensure that all length fields are properly validated before any processing occurs. This fix required modifications to the packet-ber.c file to include bounds checking and proper handling of edge cases in BER encoding, particularly around indefinite length forms and malformed length fields. The patch ensures that when invalid length values are encountered, the dissector terminates gracefully rather than entering an infinite loop, thereby maintaining the stability and availability of the Wireshark application during network traffic analysis operations. Organizations using affected Wireshark versions should immediately upgrade to patched releases to eliminate this denial of service vulnerability and maintain the integrity of their network monitoring infrastructure.