External risk intelligence

Cisco IOS SNMP Vulnerabilities Allow Code Execution or System Reload.

CVE advisoryKnown Exploit

CVE-2017-6744

A buffer overflow vulnerability in Cisco IOS Software's SNMP subsystem allows authenticated, remote attackers to execute code or cause system reloads. Exploitation requires sending a crafted SNMP packet and may involve knowing community strings or user credentials. Business risk includes unauthorized system control and

2Halo Surface Signal

Memory Corruption

Cisco Ios

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External exposure likelihood

Halo Surface Signal score for CVE-2017-6744

SNMP is typically managed within internal, restricted networks for device monitoring and administration. While network-reachable in some environments, public internet exposure of SNMP interfaces on network infrastructure is uncommon and typically discouraged by standard security practices.

Horizon Alert

Summary of the vulnerability and why it matters

The Simple Network Management Protocol (SNMP) subsystem within Cisco IOS and IOS XE Software is vulnerable to a buffer overflow. This flaw allows an authenticated, remote attacker to execute arbitrary code or cause a system reload. Exploitation is possible by sending a crafted SNMP packet to an affected system.

Vulnerable: Cisco IOS and IOS XE SNMP subsystem
Weakness: Buffer overflow in SNMP subsystem
Impact: Remote code execution or system reload

Attack Path

How an attacker could exploit the issue

This vulnerability could allow an attacker to execute code on an affected system or cause it to reload. The attack involves sending a specially crafted SNMP packet to the system. Access to the system is required, and the attacker must know SNMP community strings or user credentials, depending on the SNMP version used.

Network exposure required.
Attacker sends crafted SNMP packet.
Results in code execution or reload.

Live Threat

Current exploitation, exposure, and threat context

The identified vulnerabilities in Cisco IOS Software's SNMP subsystem present a significant risk, allowing authenticated attackers to execute code remotely or cause system reloads. Exploitation is possible through crafted SNMP packets, requiring either knowledge of SNMP read-only community strings or valid user credentials for SNMP Version 3. Successful exploitation can lead to complete system control or service disruption. The organization should treat this as a critical issue requiring immediate attention and remediation.

Attackers need authenticated access.
Exploitation involves crafted SNMP packets.
Business risk is high; treat as urgent.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in Cisco IOS Software's SNMP subsystem presents a significant risk of remote code execution or system reload. An attacker could exploit this by sending specially crafted SNMP packets. Organizations using affected Cisco IOS software should prioritize addressing this issue to prevent potential business disruption and unauthorized access.

Identify Cisco devices with SNMP enabled.
Restrict SNMP access or disable if not needed.
Apply vendor updates and verify implementation.
Monitor for unusual system activity.

Frequently asked questions

What is Cisco IOS and its SNMP subsystem?

Cisco IOS is a network operating system used on many Cisco routers and switches to manage network traffic. The SNMP subsystem is a component within IOS that allows network administrators to monitor and manage these devices using the Simple Network Management Protocol (SNMP).

What kind of weakness does CVE-2017-6744 represent?

CVE-2017-6744 is a buffer overflow vulnerability. This occurs when a program attempts to write more data into a memory buffer than it can hold, potentially corrupting adjacent memory or allowing for code execution.

What are the preconditions for an attacker to exploit this vulnerability?

An attacker must be authenticated to the target system. For SNMP versions 1 and 2c, the attacker needs to know the SNMP read-only community string. For SNMP version 3, the attacker requires user credentials for the system.

Is this vulnerability exposed to the public internet?

While the vulnerability requires network access, it is generally considered unlikely to be directly exposed to the public internet. SNMP is typically used within internal, restricted networks for device management, and public exposure is uncommon and not recommended for security reasons.

What is the first step to address this vulnerability?

The first step is to determine if SNMP is enabled on your Cisco devices. If it is enabled and not strictly required, it is recommended to disable it or restrict its access to trusted internal management networks. If SNMP is essential, applying vendor-provided software updates is the most effective solution.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.