CVE-2015-0640 in IOS XE
Summary
by MITRE
The high-speed logging (HSL) feature in Cisco IOS XE 2.x and 3.x before 3.10.4S, 3.11 before 3.11.3S, 3.12 before 3.12.1S, 3.13 before 3.13.0S, 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 large IP packets that require NAT and HSL processing after fragmentation, aka Bug ID CSCuo25741.
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Analysis
by VulDB Data Team • 04/16/2022
The vulnerability described in CVE-2015-0640 represents a critical denial of service flaw within Cisco IOS XE software versions across multiple release series. This issue specifically affects the high-speed logging feature which is designed to optimize network logging operations by processing packets more efficiently. The vulnerability manifests when devices process large IP packets that require both Network Address Translation and high-speed logging processing, creating a scenario where the device becomes unstable and eventually reloads. This flaw impacts a wide range of Cisco IOS XE versions including 2.x through 3.15.x releases, making it particularly concerning given the widespread deployment of these software versions across enterprise networks. The vulnerability is classified under CWE-121 as a buffer overflow condition, where the system fails to properly handle oversized data structures during packet processing, leading to memory corruption that ultimately causes system instability.
The technical exploitation of this vulnerability occurs when network traffic contains large IP packets that undergo fragmentation and require NAT processing within the high-speed logging subsystem. During this processing, the device attempts to handle packet data that exceeds expected buffer sizes, causing memory allocation failures that trigger device reloads. This particular flaw demonstrates how seemingly routine network operations can be weaponized to cause complete system outages. The attack vector requires remote access to the network and the ability to send specially crafted large packets that will be processed through both NAT and HSL mechanisms simultaneously. The vulnerability is particularly dangerous because it can be exploited without authentication and can cause immediate device downtime, affecting network availability and potentially disrupting business operations.
The operational impact of CVE-2015-0640 extends beyond simple device reloads to encompass broader network reliability concerns and potential business disruption. Organizations relying on affected Cisco IOS XE versions face the risk of unannounced network outages that can affect critical infrastructure, customer services, and internal communications. The vulnerability's exploitation can occur at any time during normal network operation when large packets requiring NAT and HSL processing are transmitted, making it difficult to predict or prevent. Network administrators must consider that this vulnerability could be exploited by malicious actors seeking to disrupt services or by accidental network conditions that generate large packets. The impact is particularly severe in environments where network availability is critical, such as financial institutions, telecommunications providers, or any organization where network downtime directly affects revenue or service delivery.
Mitigation strategies for CVE-2015-0640 primarily focus on software updates and network configuration adjustments. The most effective approach involves upgrading affected Cisco IOS XE versions to patched releases, specifically targeting the versions mentioned in the advisory including 3.10.4S, 3.11.3S, 3.12.1S, 3.13.0S, 3.14.0S, and 3.15.0S. Network administrators should implement monitoring solutions to detect unusual packet patterns that might indicate exploitation attempts, particularly focusing on large packets that require NAT processing. Configuration changes such as disabling high-speed logging or implementing packet filtering rules that limit large packet sizes can provide temporary protection while permanent fixes are implemented. The vulnerability aligns with ATT&CK technique T1499.004 which involves network denial of service attacks, and organizations should consider implementing network segmentation to limit the potential impact of such attacks. Security teams should also establish incident response procedures specifically addressing device reloads and ensure proper backup and recovery mechanisms are in place to minimize downtime during remediation efforts.