CVE-2013-3556 in Wireshark
Summary
by MITRE
The fragment_add_seq_common function in epan/reassemble.c in the ASN.1 BER dissector in Wireshark before r48943 has an incorrect pointer dereference during a comparison, which allows remote attackers to cause a denial of service (application crash) via a malformed packet.
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Analysis
by VulDB Data Team • 01/02/2022
The vulnerability identified as CVE-2013-3556 represents a critical denial of service flaw within Wireshark's ASN.1 BER dissector component. This issue specifically affects the fragment_add_seq_common function located in epan/reassemble.c, which is responsible for handling packet reassembly operations during network protocol analysis. The vulnerability stems from an improper pointer dereference that occurs during a comparison operation, creating a scenario where maliciously crafted packets can trigger application instability. Such flaws are particularly dangerous in network analysis tools like Wireshark, which are designed to process potentially malicious network traffic from various sources.
The technical nature of this vulnerability places it within the scope of CWE-476, which addresses NULL pointer dereference conditions that can lead to application crashes and system instability. The flaw manifests when the ASN.1 BER dissector attempts to process malformed packets that contain irregular sequence numbers or fragment identifiers. During the reassembly process, the fragment_add_seq_common function performs a comparison operation that incorrectly handles pointer validation, leading to an unexpected dereference of a null or invalid memory address. This type of error typically results in a segmentation fault or access violation that terminates the Wireshark application process, effectively rendering the network analysis tool unusable for the duration of the attack.
From an operational perspective, this vulnerability creates significant risk for network security professionals who rely on Wireshark for protocol analysis and troubleshooting. Attackers can exploit this flaw by crafting specially malformed ASN.1 BER encoded packets that, when processed by Wireshark, will cause the application to crash. The impact extends beyond simple service disruption as it can prevent security analysts from performing critical network monitoring activities during security incidents. The vulnerability is particularly concerning in environments where Wireshark is used for continuous network monitoring, as a single malicious packet can temporarily disable the monitoring capabilities. This aligns with ATT&CK technique T1499.001, which covers network disruption through application or system crashes, and demonstrates how seemingly minor implementation flaws can create substantial operational security gaps.
The mitigation strategy for CVE-2013-3556 involves updating to Wireshark versions that contain the patched implementation of the fragment_add_seq_common function. The fix typically requires proper null pointer validation before any comparison operations are performed, ensuring that memory addresses are valid before dereferencing. Network security teams should implement immediate patch management procedures to address this vulnerability, as the exploit requires no special privileges and can be executed through standard network traffic. Additionally, organizations should consider implementing network segmentation and traffic filtering mechanisms to prevent potentially malicious packets from reaching systems running Wireshark. The vulnerability demonstrates the importance of robust input validation in protocol parsing components and highlights the need for thorough testing of edge cases in network analysis tools, particularly those handling complex encoding standards like ASN.1 BER.