CVE-2015-2191 in Wireshark
Summary
by MITRE
Integer overflow in the dissect_tnef function in epan/dissectors/packet-tnef.c in the TNEF dissector in Wireshark 1.10.x before 1.10.13 and 1.12.x before 1.12.4 allows remote attackers to cause a denial of service (infinite loop) via a crafted length field in a packet.
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Analysis
by VulDB Data Team • 03/11/2022
The vulnerability identified as CVE-2015-2191 represents a critical integer overflow flaw within the TNEF dissector component of Wireshark, a widely-used network protocol analyzer. This issue affects versions 1.10.x prior to 1.10.13 and 1.12.x prior to 1.12.4, creating a persistent security risk for network analysts and security professionals who rely on Wireshark for network traffic inspection. The vulnerability specifically resides in the dissect_tnef function located in epan/dissectors/packet-tnef.c, which processes TNEF (Transport Neutral Encapsulation Format) packets commonly associated with Microsoft Outlook email attachments. TNEF packets are frequently encountered in enterprise network environments where email traffic constitutes a significant portion of network communications, making this vulnerability particularly dangerous for organizations relying on Wireshark for network monitoring and security analysis.
The technical implementation of this vulnerability stems from improper handling of length fields within TNEF packet structures during protocol dissection. When Wireshark encounters a crafted packet with an maliciously manipulated length field, the integer overflow condition causes the dissector to enter an infinite loop during packet processing. This occurs because the function fails to properly validate or clamp the length value before using it in loop conditions or memory allocation calculations. The overflow results in the loop counter becoming negative or excessively large, causing the dissection process to continue indefinitely without proper termination. This behavior fundamentally breaks the expected packet processing flow and transforms a legitimate network analysis tool into a denial of service vector that can be exploited by remote attackers. The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and demonstrates how improper input validation can lead to system instability and resource exhaustion.
The operational impact of CVE-2015-2191 extends beyond simple denial of service, creating significant risks for network security operations and incident response activities. When exploited, this vulnerability can cause Wireshark to consume excessive CPU resources and become unresponsive, effectively rendering network analysis capabilities useless during critical security events. Network security teams who depend on real-time packet analysis for threat detection, forensic investigation, or network troubleshooting may find their monitoring tools unavailable when attackers craft malicious TNEF packets. This vulnerability particularly impacts enterprise environments where email traffic is substantial and where Wireshark is commonly used for network forensics. The infinite loop condition can persist for extended periods, potentially causing system resource exhaustion and impacting other network services that may be running on the same analysis infrastructure. Organizations using Wireshark for continuous network monitoring face a heightened risk of operational disruption, especially during security incidents when real-time analysis capabilities are most critical.
Mitigation strategies for CVE-2015-2191 should prioritize immediate software updates to patched versions of Wireshark, specifically versions 1.10.13 and 1.12.4 or later. Network administrators should implement network segmentation and access controls to limit exposure to potentially malicious traffic, particularly in environments where TNEF packets are frequently encountered. The implementation of network-based intrusion detection systems can help identify and block suspicious packet patterns associated with this vulnerability. Additionally, organizations should consider implementing network traffic filtering rules to drop or quarantine TNEF packets from untrusted sources, reducing the attack surface. From a defensive perspective, this vulnerability highlights the importance of input validation and proper boundary checking in protocol dissector implementations, aligning with ATT&CK technique T1059.007 for execution through command and scripting interpreter and T1499.004 for network disruption. Security teams should also consider implementing automated patch management processes to ensure rapid deployment of security updates across network analysis infrastructure, preventing similar vulnerabilities from being exploited in operational environments.