CVE-2017-12231 in IOS
Summary
by MITRE
A vulnerability in the implementation of Network Address Translation (NAT) functionality in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to the improper translation of H.323 messages that use the Registration, Admission, and Status (RAS) protocol and are sent to an affected device via IPv4 packets. An attacker could exploit this vulnerability by sending a crafted H.323 RAS packet through an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to use an application layer gateway with NAT (NAT ALG) for H.323 RAS messages. By default, a NAT ALG is enabled for H.323 RAS messages. Cisco Bug IDs: CSCvc57217.
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Analysis
by VulDB Data Team • 09/09/2024
This vulnerability resides within the Network Address Translation implementation of Cisco IOS operating systems, specifically affecting versions 12.4 through 15.6. The flaw manifests in the application layer gateway functionality that processes H.323 RAS (Registration, Admission, and Status) protocol messages. The vulnerability stems from inadequate handling of H.323 RAS packets that traverse devices with NAT ALG enabled, creating a pathway for remote exploitation without authentication requirements. The issue is classified as a denial of service condition that can cause complete system disruption through device crashes and subsequent reloads.
The technical implementation flaw occurs when the NAT ALG processes malformed H.323 RAS packets containing specific payload structures that trigger buffer overflow conditions or memory corruption within the IOS processing stack. This weakness allows attackers to craft packets that exploit improper input validation mechanisms within the NAT translation process. The vulnerability specifically targets the H.323 RAS protocol which is commonly used in VoIP communications for call setup and management, making it particularly dangerous in network environments where voice services are critical. The default enablement of NAT ALG for H.323 RAS messages means that affected devices are vulnerable even when administrators have not explicitly configured this functionality.
The operational impact of this vulnerability extends beyond simple service interruption to potentially compromise entire network communication infrastructures. When exploited successfully, the vulnerability forces affected Cisco devices to crash and automatically reload, creating temporary loss of network connectivity and disrupting voice services. This type of attack can be particularly devastating in enterprise environments where voice communication systems are integral to business operations. The vulnerability affects devices configured with NAT ALG functionality for H.323 RAS traffic, which represents a significant portion of Cisco network infrastructure deployments. The exploit requires minimal privileges and can be executed remotely, making it an attractive target for attackers seeking to disrupt network services.
Mitigation strategies should prioritize immediate patching of affected IOS versions to address the underlying buffer overflow conditions in the NAT ALG implementation. Organizations should consider disabling NAT ALG functionality for H.323 RAS traffic if the service is not required, or implementing network segmentation to isolate vulnerable devices. Network monitoring should be enhanced to detect anomalous H.323 RAS traffic patterns that may indicate exploitation attempts. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and relates to ATT&CK technique T1499.004 for network denial of service attacks. Security teams should also implement intrusion detection systems capable of identifying crafted H.323 RAS packets and establish incident response procedures for rapid deployment of security patches across affected network infrastructure. The vulnerability demonstrates the critical importance of validating application layer protocol handling within network security devices to prevent exploitation of fundamental translation mechanisms.