CVE-2015-6272 in IOS XE
Summary
by MITRE
Cisco IOS XE 2.1.0 through 2.2.3 and 2.3.0 on ASR 1000 devices, when NAT Application Layer Gateway is used, allows remote attackers to cause a denial of service (Embedded Services Processor crash) via a crafted H.323 packet, aka Bug ID CSCsx35393, CSCsx07094, and CSCsw93064.
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Analysis
by VulDB Data Team • 06/13/2022
The vulnerability CVE-2015-6272 represents a critical denial of service flaw affecting Cisco IOS XE software versions 2.1.0 through 2.2.3 and 2.3.0 running on ASR 1000 series devices. This weakness specifically manifests when the NAT Application Layer Gateway feature is enabled, creating a pathway for remote attackers to exploit the system through carefully crafted H.323 packets. The flaw resides in the Embedded Services Processor component of the device architecture, which handles various network services including application layer processing and packet inspection. The vulnerability impacts the core functionality of the device by causing the Embedded Services Processor to crash, effectively rendering the device unable to process network traffic and resulting in a complete denial of service condition that can disrupt critical network operations. This issue affects organizations relying on ASR 1000 routers for voice and data services, particularly those utilizing H.323 protocol for VoIP communications, as the attack can be executed remotely without requiring authentication or physical access to the device.
The technical exploitation of this vulnerability occurs through malformed H.323 packets that are specifically designed to trigger a buffer overflow or memory corruption condition within the Embedded Services Processor when processing these packets through the NAT Application Layer Gateway functionality. The flaw demonstrates characteristics consistent with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors that can lead to system crashes. When the processor encounters these crafted packets, it fails to properly validate input data or handle memory allocation, leading to an uncontrolled crash that requires manual intervention to restore normal device operation. The vulnerability is particularly concerning because it operates at the application layer gateway level where network traffic is inspected and processed, making it a critical point of failure that can impact the entire network infrastructure relying on these devices for traffic management and security services.
The operational impact of CVE-2015-6272 extends beyond simple service disruption, as it can compromise network reliability and availability for organizations that depend on ASR 1000 series routers for their core network operations. The remote nature of the attack means that malicious actors can exploit this vulnerability from anywhere on the network, potentially targeting critical infrastructure components without detection or authorization. This vulnerability aligns with ATT&CK technique T1498, which describes denial of service attacks, and T1595, which covers network boundary exploitation techniques. Organizations may experience significant downtime as network administrators must respond to the crash, restore system functionality, and implement temporary workarounds while waiting for official patches. The vulnerability also impacts network security posture by potentially allowing attackers to gain insight into network infrastructure configurations and operational patterns, as the crash may reveal information about the device's internal state and configuration details.
Mitigation strategies for CVE-2015-6272 should focus on immediate defensive measures while longer-term solutions are implemented. Organizations should disable the NAT Application Layer Gateway functionality on affected devices until patches are applied, as this removes the attack surface that enables the vulnerability. Network segmentation and access controls should be implemented to limit exposure of affected devices to untrusted networks, reducing the potential attack vectors available to remote adversaries. The Cisco Security Advisory provides specific guidance for applying patches and implementing workarounds, including firmware updates that address the underlying buffer overflow conditions in the Embedded Services Processor. Security monitoring should be enhanced to detect unusual traffic patterns or potential exploitation attempts, with network administrators implementing intrusion detection systems that can identify malformed H.323 packets. Additionally, organizations should conduct thorough vulnerability assessments to identify all affected devices and establish incident response procedures to address potential exploitation attempts, ensuring that network availability and security are maintained during the remediation process.