CVE-2014-7207 in Linux
Summary
by MITRE
A certain Debian patch to the IPv6 implementation in the Linux kernel 3.2.x through 3.2.63 does not properly validate arguments in ipv6_select_ident function calls, which allows local users to cause a denial of service (NULL pointer dereference and system crash) by leveraging (1) tun or (2) macvtap device access.
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Analysis
by VulDB Data Team • 02/24/2022
The vulnerability identified as CVE-2014-7207 represents a critical flaw in the Linux kernel's IPv6 implementation that specifically affects versions 3.2.x through 3.2.63. This issue stems from a Debian-specific patch that was intended to address certain IPv6 behaviors but inadvertently introduced a significant security weakness. The vulnerability manifests within the ipv6_select_ident function, which is responsible for selecting appropriate identification values for IPv6 packets. The flaw occurs when this function fails to properly validate input arguments, creating a pathway for malicious exploitation that can result in system-wide disruption.
The technical nature of this vulnerability places it firmly within the realm of kernel-level security flaws, specifically categorized under CWE-20 as "Improper Input Validation" and CWE-476 as "NULL Pointer Dereference." When local users gain access to tun or macvtap network devices, they can exploit this weakness by crafting specific arguments that trigger the vulnerable function. The exploitation process leverages the fact that the ipv6_select_ident function does not adequately check parameter boundaries or validity before processing them. This allows attackers to pass malformed or unexpected arguments that cause the kernel to attempt to dereference a NULL pointer, resulting in an immediate system crash and complete denial of service condition.
The operational impact of CVE-2014-7207 extends beyond simple system instability, as it provides attackers with a reliable method for causing persistent service disruption. Local users who can access tun or macvtap devices can repeatedly trigger the vulnerability to maintain system unavailability, making this particularly concerning for environments where such device access might be granted to untrusted users or processes. The vulnerability's exploitation requires minimal privileges beyond access to the affected network device types, making it especially dangerous in multi-user systems or containerized environments where privilege escalation might be limited but device access remains possible. This flaw directly impacts the availability aspect of the CIA triad by creating conditions that can permanently disable system networking capabilities until manual intervention occurs.
From an ATT&CK framework perspective, this vulnerability aligns with techniques related to privilege escalation and denial of service operations. The attack vector specifically maps to T1068 as "Exploitation for Privilege Escalation" and T1499 as "Endpoint Denial of Service" within the adversary tactics. Organizations should implement immediate mitigations including kernel version updates to versions beyond 3.2.63, where the Debian patch was corrected to properly validate function arguments. Additionally, network device access controls should be tightened to limit which users or processes can interact with tun and macvtap interfaces. System administrators should also consider implementing monitoring solutions that can detect unusual patterns of system crashes or network device access that might indicate exploitation attempts, as these vulnerabilities often leave detectable traces in system logs and network traffic patterns.