CVE-2015-0633 in Unified Computing System
Summary
by MITRE
The Integrated Management Controller (IMC) in Cisco Unified Computing System (UCS) 1.4(7h) and earlier on C-Series servers allows remote attackers to bypass intended access restrictions by sending crafted DHCP response packets on the local network, aka Bug ID CSCuf52876.
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Analysis
by VulDB Data Team • 04/16/2022
The vulnerability described in CVE-2015-0633 represents a significant security flaw within Cisco Unified Computing System's Integrated Management Controller implementation. This issue affects UCS versions 1.4(7h) and earlier, specifically targeting C-Series servers that rely on the IMC for out-of-band management functions. The vulnerability stems from inadequate validation of DHCP responses within the management controller's network stack, creating a pathway for unauthorized network access that bypasses established security boundaries.
The technical exploitation of this vulnerability occurs through the manipulation of DHCP response packets transmitted across the local network segment. Attackers can craft and inject malicious DHCP responses that the IMC accepts without proper authentication verification, effectively allowing unauthorized entities to establish network connectivity and potentially gain access to the management plane of the server. This flaw operates at the network protocol level, specifically targeting the Dynamic Host Configuration Protocol implementation within the IMC firmware. The vulnerability is classified under CWE-284, which addresses improper access control mechanisms, and represents a classic case of insufficient input validation that allows malicious packet injection to be accepted as legitimate network configuration data.
The operational impact of this vulnerability extends beyond simple network access, as it enables attackers to potentially compromise the entire management infrastructure of affected servers. Remote attackers who can position themselves on the same local network segment can exploit this weakness to gain unauthorized access to the IMC's management interface, potentially leading to full system compromise. This represents a critical threat to data center security, as the IMC serves as the primary interface for server administration and monitoring functions. The vulnerability enables attackers to bypass network segmentation controls that should normally isolate management traffic from regular network operations, creating a persistent threat vector that can be exploited without requiring physical access to the server hardware.
Organizations implementing Cisco UCS systems must prioritize immediate remediation through firmware updates provided by Cisco to address this vulnerability. The recommended mitigation strategy involves applying the latest firmware patches that correct the DHCP response validation logic within the IMC. Network segmentation measures should be implemented to isolate management traffic from production networks, though this approach provides only partial protection as the vulnerability can be exploited through local network access. Additional defensive measures include implementing network access controls to limit which devices can respond to DHCP requests within the local network segment, and deploying network monitoring solutions to detect anomalous DHCP activity that may indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1046, which covers network service scanning, and demonstrates how weaknesses in network protocol implementation can create persistent access vectors that undermine fundamental security controls. The incident highlights the critical importance of validating all network communications, particularly those involving configuration protocols like DHCP that are essential for network infrastructure operations but can become attack vectors when not properly secured.