CVE-2017-6615 in IOS XE
Summary
by MITRE
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE 3.16 could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to a race condition that could occur when the affected software processes an SNMP read request that contains certain criteria for a specific object ID (OID) and an active crypto session is disconnected on an affected device. An attacker who can authenticate to an affected device could trigger this vulnerability by issuing an SNMP request for a specific OID on the device. A successful exploit will cause the device to restart due to an attempt to access an invalid memory region. The attacker does not control how or when crypto sessions are disconnected on the device. Cisco Bug IDs: CSCvb94392.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability identified as CVE-2017-6615 resides within the Simple Network Management Protocol subsystem of Cisco IOS XE software version 3.16, presenting a significant security risk that could be exploited by authenticated remote attackers to induce denial of service conditions. This flaw specifically manifests when the system processes certain SNMP read requests containing particular object identifiers while concurrent crypto sessions are being terminated, creating a precarious race condition scenario that fundamentally undermines system stability. The vulnerability operates through a complex interaction between SNMP processing mechanisms and cryptographic session management, where the timing of these operations creates an exploitable window that leads to system instability.
The technical exploitation of this vulnerability requires an authenticated attacker who can successfully establish communication with the affected Cisco IOS XE device, enabling them to craft and submit specific SNMP requests targeting designated object identifiers. The race condition occurs during the processing of these requests when the system attempts to access memory regions that have already been invalidated due to the disconnection of active crypto sessions. This memory access violation triggers a system crash that ultimately results in device restart, effectively disrupting network services and potentially creating unauthorized access opportunities for malicious actors. The vulnerability's design flaw stems from inadequate synchronization mechanisms between SNMP request processing and crypto session lifecycle management, creating an exploitable state where memory references become invalid during concurrent operations.
The operational impact of CVE-2017-6615 extends beyond simple service disruption, as the device restart caused by this vulnerability can lead to extended network outages and potential cascading failures within larger network infrastructures. Network administrators face the challenge of maintaining availability while dealing with the unpredictable nature of crypto session disconnections that trigger this condition, making it particularly dangerous in mission-critical environments where uptime is paramount. The vulnerability's exploitation does not require advanced privileges beyond authentication, making it accessible to attackers who may already have legitimate network access, thereby increasing the potential for both accidental and intentional disruption. This characteristic aligns with ATT&CK technique T1499.004 for network denial of service and CWE-362 for race conditions, demonstrating how improper synchronization can create exploitable security weaknesses.
Mitigation strategies for this vulnerability require immediate implementation of Cisco's recommended security patches and updates, as the manufacturer has addressed this specific race condition through firmware modifications that enhance synchronization between SNMP processing and crypto session management. Network administrators should also implement monitoring solutions to detect anomalous SNMP activity patterns and crypto session disconnection events that may precede exploitation attempts. The security community recognizes this vulnerability as particularly concerning due to its potential for automated exploitation and the difficulty in predicting when crypto sessions will disconnect, making proactive patch management essential. Additionally, implementing network segmentation and access controls can help limit the potential impact of successful exploitation attempts, while regular security assessments should verify that systems remain protected against similar race condition vulnerabilities that may exist in other network management protocols.