CVE-2016-1424 in IOS
Summary
by MITRE
Cisco IOS 15.2(1)T1.11 and 15.2(2)TST allows remote attackers to cause a denial of service (device crash) via a crafted LLDP packet, aka Bug ID CSCun63132.
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Analysis
by VulDB Data Team • 10/14/2024
Cisco IOS devices running versions 15.2(1)T1.11 and 15.2(2)TST contain a critical vulnerability that enables remote attackers to trigger a denial of service condition through the careful construction of Link Layer Discovery Protocol packets. This vulnerability represents a classic buffer overflow scenario where the device fails to properly validate incoming LLDP frames, leading to memory corruption that ultimately results in system instability and complete device crash. The flaw exists within the LLDP processing module of the IOS operating system, specifically in how it handles malformed or oversized LLDP TLVs (Type-Length-Value) fields that are part of the standard LLDP protocol implementation.
The technical exploitation of this vulnerability requires an attacker to send a specially crafted LLDP packet to the target device, which then processes this malformed data without adequate input validation. When the device attempts to parse the crafted TLV structure, it encounters unexpected data patterns that cause the memory management routines to fail, leading to a system crash and subsequent denial of service. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and specifically relates to improper input validation within network protocol handlers. The attack vector is remote and does not require authentication, making it particularly dangerous as any network-connected device running the vulnerable IOS version can be targeted.
The operational impact of this vulnerability extends beyond simple service disruption, as it can lead to significant network reliability issues when multiple devices in a network infrastructure are affected simultaneously. Network administrators may experience complete loss of connectivity to affected devices, requiring manual intervention to reboot systems and restore normal operations. The vulnerability affects Cisco IOS devices across multiple platforms including routers and switches, making it a widespread concern for enterprise network environments where LLDP is commonly used for device discovery and network management. According to ATT&CK framework, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1595.001, representing network device compromise through protocol manipulation.
Organizations should immediately implement mitigations including applying the relevant Cisco security patches and updates to resolve the vulnerability. Network segmentation strategies can help limit the impact of such attacks by isolating vulnerable devices from critical network segments. Additionally, implementing LLDP filtering rules at network boundaries can prevent malformed LLDP packets from reaching vulnerable devices. Monitoring systems should be configured to detect unusual traffic patterns that may indicate exploitation attempts, and regular security assessments should verify that all network devices are running patched versions of IOS software. The vulnerability highlights the importance of proper input validation in network protocol implementations and demonstrates how seemingly benign network discovery protocols can become attack vectors when not properly secured against malformed data inputs.