CVE-2002-1976 in Linux
Summary
by MITRE
ifconfig, when used on the Linux kernel 2.2 and later, does not report when the network interface is in promiscuous mode if it was put in promiscuous mode using PACKET_MR_PROMISC, which could allow attackers to sniff the network without detection, as demonstrated using libpcap.
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Analysis
by VulDB Data Team • 07/07/2024
The vulnerability described in CVE-2002-1976 represents a significant security flaw in the Linux networking stack that affects kernel versions 2.2 and later. This issue specifically impacts the ifconfig utility's ability to accurately report network interface states, creating a covert channel for malicious actors to conduct network surveillance without detection. The flaw arises from a mismatch between how the kernel manages promiscuous mode through the PACKET_MR_PROMISC mechanism and how the user-space utility reports this state to administrators.
The technical root cause of this vulnerability stems from the Linux kernel's packet capture subsystem and its interaction with the ifconfig command. When a network interface is placed into promiscuous mode using the PACKET_MR_PROMISC multicast receive mode flag, the kernel correctly sets the interface to capture all packets on the network segment. However, the ifconfig utility fails to properly query or interpret the kernel's internal state that indicates promiscuous mode status. This discrepancy creates a false positive scenario where network administrators believe interfaces are operating normally, while in reality they are capturing all network traffic.
From an operational perspective, this vulnerability enables sophisticated network reconnaissance and surveillance activities that bypass standard security monitoring mechanisms. Attackers can leverage this flaw to place network interfaces into promiscuous mode using libpcap or similar packet capture libraries without the system's network administrators being aware of the change. The implications extend beyond simple packet sniffing to include potential man-in-the-middle attacks, credential harvesting, and comprehensive network traffic analysis that would normally be detectable through proper network monitoring. This vulnerability directly aligns with attack techniques documented in the MITRE ATT&CK framework under the Network Sniffing and Credential Access domains.
The security impact of CVE-2002-1976 is particularly concerning given that it operates at the kernel level and affects fundamental network monitoring capabilities. Network administrators relying on standard ifconfig output for security auditing and monitoring may unknowingly allow persistent surveillance of their network segments. The vulnerability demonstrates a critical gap in the Linux kernel's user-space interface communication, where the kernel's internal state management does not properly synchronize with the reporting mechanisms available to system administrators. This flaw represents a classic example of information disclosure through incomplete state reporting, which can be categorized under CWE-200 (Information Exposure) and CWE-123 (Bind-Address to Port Mapping) in the CWE database.
Mitigation strategies for this vulnerability require both immediate and long-term approaches. System administrators should implement comprehensive network monitoring solutions that go beyond basic ifconfig output, including tools that directly query kernel network statistics and packet capture capabilities. Regular security auditing should include verification of network interface states through multiple methods rather than relying solely on ifconfig output. The most effective long-term solution involves kernel-level patches that ensure proper synchronization between the kernel's promiscuous mode state and user-space reporting mechanisms. Additionally, implementing network access control lists and intrusion detection systems can help detect anomalous network traffic patterns that may indicate unauthorized promiscuous mode activation. Organizations should also consider deploying network segmentation and monitoring solutions that can detect and alert on suspicious network behavior regardless of the interface state reporting accuracy.