CVE-2012-4623 in IOS
Summary
by MITRE
The DHCPv6 server in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x, 3.1.xS before 3.1.4S, 3.1.xSG and 3.2.xSG before 3.2.5SG, 3.2.xS, 3.2.xXO, 3.3.xS, and 3.3.xSG before 3.3.1SG allows remote attackers to cause a denial of service (device reload) via a malformed DHCPv6 packet, aka Bug ID CSCto57723.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability described in CVE-2012-4623 represents a critical denial of service flaw affecting Cisco IOS and IOS XE operating systems across multiple version ranges. This vulnerability specifically targets the DHCPv6 server implementation within Cisco networking devices, making it particularly dangerous for network infrastructure components that rely on dynamic address assignment for IPv6 connectivity. The flaw enables remote attackers to exploit a malformed DHCPv6 packet structure that causes the affected devices to crash and subsequently reload their operating systems, resulting in complete service disruption for network users.
The technical root cause of this vulnerability lies in inadequate input validation within the DHCPv6 server processing logic. When the DHCPv6 server receives a malformed packet containing improperly structured options or fields, the parsing routine fails to properly handle the unexpected data format, leading to memory corruption or stack overflow conditions. This type of vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors. The vulnerability's exploitation mechanism allows attackers to craft specific DHCPv6 packets that trigger the device's processing routine to execute unintended code paths, ultimately causing the system to reboot automatically.
From an operational impact perspective, this vulnerability poses significant risk to network availability and stability, particularly in enterprise and service provider environments where Cisco devices serve as core infrastructure components. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring physical access or authentication credentials. The resulting device reload creates temporary network outages that can disrupt critical services, affect business operations, and potentially compromise network security posture during the recovery period. Network administrators may experience cascading failures if multiple devices in the same network segment are affected, leading to widespread connectivity issues.
The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for Network Denial of Service, as it specifically targets network infrastructure components to create service disruptions. Organizations should implement immediate mitigations including applying the latest Cisco IOS patches and IOS XE software releases that address the DHCPv6 parsing flaw. Network segmentation strategies can help limit the attack surface, while implementing DHCPv6 filtering rules at network boundaries can prevent malformed packets from reaching vulnerable devices. Additionally, monitoring for unusual DHCPv6 traffic patterns and implementing intrusion detection systems can help detect exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date network device firmware and implementing robust input validation mechanisms to prevent similar issues in future deployments.