CVE-2015-0771 in IOS
Summary
by MITRE
The IKE implementation in the WS-IPSEC-3 service module in Cisco IOS 12.2 on Catalyst 6500 devices allows remote authenticated users to cause a denial of service (device reload) by sending a crafted message during IPsec tunnel setup, aka Bug ID CSCur70505.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/21/2022
The vulnerability identified as CVE-2015-0771 represents a critical denial of service weakness within Cisco IOS 12.2 software running on Catalyst 6500 series switches. This flaw specifically affects the WS-IPSEC-3 service module's implementation of the Internet Key Exchange protocol, which is fundamental to establishing secure IPsec tunnels between network devices. The vulnerability operates through a carefully crafted message that can be transmitted during the initial IPsec tunnel setup phase, exploiting a flaw in the IKE processing logic that leads to complete device system reload.
The technical nature of this vulnerability stems from insufficient input validation within the IKE implementation, where the WS-IPSEC-3 module fails to properly handle malformed or specially constructed IKE messages during the negotiation process. This weakness allows an authenticated attacker who has access to the network to send maliciously formatted packets that trigger an unhandled exception in the device's processing stack. The flaw specifically manifests when the device encounters certain sequence numbers or message structures that are not properly validated against expected parameters, causing the system to crash and subsequently reboot. This behavior aligns with CWE-129, which addresses improper validation of input boundaries, and CWE-248, which covers exposure of an uninitialized exception handler.
From an operational perspective, this vulnerability presents a significant risk to network availability as it allows remote authenticated attackers to disrupt network services without requiring privileged access to the device itself. The impact extends beyond simple service interruption since the device reload process can affect multiple network segments depending on the role of the affected switch in the network topology. Network administrators may experience extended downtime as the device reboots and re-establishes connections, potentially causing cascading failures if the switch serves as a core routing point or if multiple tunnels are affected simultaneously. The vulnerability affects devices running Cisco IOS 12.2 software specifically, making it particularly concerning for organizations maintaining legacy network infrastructure where software updates may not be immediately available.
The security implications of this vulnerability extend to the broader ATT&CK framework, particularly under the T1499.004 technique for Network Denial of Service, and T1566 for Phishing with Social Engineering. The attack vector requires authentication, which places it in the category of authenticated attacks that can be particularly challenging to detect and prevent since legitimate users may be exploited. Mitigation strategies should focus on implementing network segmentation to limit access to the affected service modules, applying the appropriate Cisco IOS patches, and monitoring for unusual IKE traffic patterns that may indicate exploitation attempts. Organizations should also consider implementing access controls that restrict the number of authenticated users who can establish IPsec connections, as well as network monitoring solutions that can detect and alert on anomalous IKE message sequences that may precede the denial of service condition. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and the potential consequences of relying on legacy network infrastructure without proper security controls in place.