CVE-2016-1428 in IOS XE
Summary
by MITRE
Double free vulnerability in Cisco IOS XE 3.15S, 3.16S, and 3.17S allows remote authenticated users to cause a denial of service (device restart) via a sequence of crafted SNMP read requests, aka Bug ID CSCux13174.
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Analysis
by VulDB Data Team • 01/31/2019
The vulnerability identified as CVE-2016-1428 represents a critical double free condition within Cisco IOS XE software versions 3.15S, 3.16S, and 3.17S that manifests through SNMP read request handling. This flaw resides in the network operating system's memory management routines where improper handling of specific SNMP packet sequences triggers erroneous memory deallocation patterns. The vulnerability specifically affects the SNMP service implementation within the IOS XE framework, creating a scenario where the same memory block can be freed twice, leading to unpredictable system behavior and potential device instability. The issue stems from inadequate input validation and memory management controls within the SNMP subsystem, particularly when processing crafted read requests that exploit the underlying software architecture.
The technical exploitation of this vulnerability requires an authenticated attacker who can send specifically crafted SNMP read requests to the affected device. The sequence of requests must be carefully constructed to trigger the double free condition within the memory allocator, causing the system to attempt to free the same memory block twice. This memory corruption leads to a cascade of system failures that ultimately result in device reboot or complete system restart. The vulnerability's remote nature means that authenticated users with access to the SNMP service can leverage this flaw without requiring physical access to the device. The attack vector operates through the standard SNMP protocol implementation, making it particularly dangerous as it can be exploited through normal network operations. The double free condition creates a memory heap corruption that manifests as system instability and can be reliably reproduced through specific SNMP request sequences.
The operational impact of this vulnerability extends beyond simple denial of service, as device restarts can disrupt network services and potentially create security gaps during the reboot process. Network administrators may experience unexpected downtime across critical infrastructure components, particularly in environments where Cisco IOS XE devices serve as core network elements. The vulnerability affects enterprise network infrastructure, including routers and switches running the affected software versions, potentially impacting large-scale deployments where multiple devices may be simultaneously vulnerable. The remote authentication requirement means that insider threats or compromised accounts could exploit this vulnerability, making it particularly concerning for organizations with less stringent access controls. The instability introduced by the double free condition could also potentially mask other underlying security issues or create opportunities for further exploitation.
Mitigation strategies for CVE-2016-1428 should prioritize immediate software updates to the latest IOS XE releases that contain patches addressing the memory management flaw. Cisco released specific software updates to resolve this vulnerability, and organizations should implement these patches as part of their regular security maintenance procedures. Network segmentation and access control measures can help limit the potential impact by restricting SNMP access to only authorized administrative systems. Monitoring SNMP traffic for unusual patterns or sequences of read requests may help detect exploitation attempts before they succeed. The vulnerability aligns with CWE-415, which describes improper behavior in memory management where a program frees the same memory block twice, and relates to ATT&CK technique T1072 for the use of application or system binaries that execute commands. Organizations should also consider implementing network-based intrusion detection systems to monitor for potential exploitation attempts and maintain comprehensive network documentation to quickly identify affected devices. Regular security assessments and vulnerability scanning should include verification of IOS XE versions to ensure all devices are running patched software releases.