CVE-2007-2480 in Linux
Summary
by MITRE
The _udp_lib_get_port function in net/ipv4/udp.c in Linux kernel 2.6.21 and earlier does not prevent a bind to a port with a local address when there is already a bind to that port with a wildcard local address, which might allow local users to intercept local traffic for daemons or other applications.
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Analysis
by VulDB Data Team • 04/13/2019
The vulnerability described in CVE-2007-2480 resides within the Linux kernel's UDP networking implementation, specifically in the _udp_lib_get_port function located in net/ipv4/udp.c. This flaw represents a significant security weakness that affects Linux kernel versions 2.6.21 and earlier, creating an improper access control scenario where local users can potentially intercept network traffic intended for other applications. The issue stems from the kernel's failure to properly enforce port binding rules when multiple applications attempt to bind to the same UDP port under different address specifications.
The technical root cause of this vulnerability lies in the insufficient validation within the _udp_lib_get_port function which handles UDP port allocation and binding operations. When a daemon or application binds to a UDP port using a wildcard address (0.0.0.0 or INADDR_ANY), the kernel correctly allocates that port for all local interfaces. However, the function fails to prevent a subsequent bind operation to the same port when specifying a particular local address, creating a scenario where the second binding effectively overrides or conflicts with the first. This behavior violates fundamental socket programming principles and creates a race condition that local attackers can exploit to capture traffic destined for other processes.
The operational impact of this vulnerability extends beyond simple traffic interception, as it enables local users to perform man-in-the-middle attacks against local network services. Attackers can leverage this flaw to capture and potentially modify data sent to UDP services that are already bound to specific local addresses, compromising the confidentiality and integrity of network communications. This vulnerability particularly affects services that rely on UDP for communication and are running with elevated privileges, as it allows local privilege escalation through traffic interception and manipulation. The implications are especially severe in environments where multiple applications share common UDP ports or where network services are not properly secured against local attacks.
From a cybersecurity perspective, this vulnerability maps directly to CWE-1216, which addresses improper access control in network services, and aligns with ATT&CK technique T1071.004 for Application Layer Protocol: DNS. The flaw demonstrates how kernel-level networking components can create security gaps that allow local privilege escalation through network traffic manipulation. Organizations should implement immediate mitigations including kernel updates to versions 2.6.22 and later where this vulnerability has been addressed, along with network segmentation and proper access controls to limit local user privileges. Additionally, administrators should monitor for unauthorized socket binding operations and implement network intrusion detection systems to identify potential exploitation attempts, as the vulnerability can be leveraged by attackers who have local access to compromised systems to gain unauthorized access to network services.