Vulnerability in Cisco IOS Software in SNMP subsystem

This vulnerability in Cisco IOS Software and Cisco IOS XE Software resides in the SNMP (Simple Network Management Protocol) subsystem and can allow an authenticated, remote attacker to cause a Denial-of-Service (DoS) condition on an affected device.

Vulnerability in Cisco IOS Software in SNMP subsystem

Key Details of the Vulnerability:

  • Cause: The issue arises due to improper error handling when parsing SNMP requests.
  • Impact: If exploited successfully, the vulnerability forces the affected device to reload (crash and restart), leading to a DoS condition.
  • SNMP Versions Affected:
    • SNMPv1 & SNMPv2c: To exploit the flaw, the attacker must know a valid read-write or read-only SNMP community string (which acts like a password).
    • SNMPv3: The attacker must have valid SNMP user credentials for the targeted system.

Exploitation Process:

  1. The attacker sends a specially crafted SNMP request to the vulnerable device.
  2. Due to improper error handling, the system fails to process the request correctly.
  3. This results in an unexpected reload (crash) of the device, leading to service disruption.

Potential Impact:

  • Affected network devices (such as routers and switches) could become unavailable, leading to network downtime.
  • Attackers with valid SNMP credentials could repeatedly exploit the flaw to disrupt network operations.

Mitigation & Protection:

  • Restrict SNMP Access: Limit SNMP access to trusted IP addresses.
  • Use SNMPv3 with Strong Authentication: SNMPv3 offers better security with encryption and authentication—ensure that strong credentials are used.
  • Apply Cisco Patches: Cisco may have released software updates to fix this issue—updating to a patched version is highly recommended.
  • Monitor SNMP Traffic: Use network monitoring tools to detect suspicious SNMP requests.

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