CVE-2015-0645 in IOS XE
Summary
by MITRE
The Layer 4 Redirect (L4R) feature in Cisco IOS XE 2.x and 3.x before 3.10.4S, 3.11 before 3.11.3S, 3.12 before 3.12.2S, 3.13 before 3.13.1S, 3.14 before 3.14.0S, and 3.15 before 3.15.0S allows remote attackers to cause a denial of service (device reload) via malformed (1) IPv4 or (2) IPv6 packets, aka Bug ID CSCuq59131.
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Analysis
by VulDB Data Team • 04/16/2022
The vulnerability described in CVE-2015-0645 represents a critical denial of service flaw within Cisco IOS XE software versions affecting multiple release branches. This issue specifically targets the Layer 4 Redirect functionality, which is designed to facilitate network traffic redirection based on Layer 4 protocol information. The vulnerability manifests when the system processes malformed IPv4 or IPv6 packets that are crafted to exploit weaknesses in the packet handling mechanisms of the L4R feature. According to the Cisco bug identification system, this flaw was catalogued as CSCuq59131 and demonstrates how seemingly benign network traffic can be weaponized to cause complete device restarts.
The technical exploitation of this vulnerability occurs through the manipulation of packet structures that are processed by the Layer 4 Redirect component of the IOS XE operating system. When the system receives malformed IPv4 or IPv6 packets, the parsing logic within the L4R feature fails to properly validate or handle these malformed structures, leading to a condition where the device's memory management or processing threads become corrupted. This corruption ultimately results in an uncontrolled system reload that effectively denies network services to legitimate users. The vulnerability demonstrates characteristics consistent with memory corruption issues typically classified under CWE-125, where insufficient bounds checking allows for improper memory access.
The operational impact of this vulnerability extends beyond simple service disruption as it can be leveraged by remote attackers to perform sustained denial of service attacks against targeted network infrastructure. Network administrators operating affected Cisco devices face the risk of unauthorized service interruption, potentially affecting critical network operations and business continuity. The vulnerability affects multiple release versions of IOS XE, indicating a widespread exposure across various network equipment deployments. Attackers need only send specially crafted malformed packets to trigger the device reload, making this a particularly dangerous vulnerability as it requires minimal expertise to exploit and can be automated for large-scale attacks.
Mitigation strategies for CVE-2015-0645 primarily involve applying the vendor-provided security patches and updates that address the underlying packet processing flaws in the L4R feature. Network administrators should prioritize upgrading affected devices to versions 3.10.4S, 3.11.3S, 3.12.2S, 3.13.1S, 3.14.0S, and 3.15.0S or later, as these releases contain the necessary fixes to prevent the malformed packet exploitation. Additional defensive measures include implementing network access control lists to filter suspicious traffic patterns and monitoring for unusual packet structures that might indicate attempted exploitation. From an ATT&CK framework perspective, this vulnerability aligns with the T1499.004 technique for network denial of service, where adversaries leverage system vulnerabilities to disrupt network services. The vulnerability also demonstrates characteristics of T1595.001 for reconnaissance, as attackers may need to identify affected systems before launching exploitation attempts. Organizations should consider implementing network segmentation and traffic monitoring to detect and prevent exploitation attempts, while maintaining up-to-date threat intelligence regarding similar vulnerabilities in network infrastructure components.