CVE-2022-20711 – This critical vulnerability in Cisco Small Busi... (How to Fix)

Q: What is the severity of CVE-2022-20711?

CVE-2022-20711 has a CVSS score of 10.0 (CRITICAL). This critical vulnerability in Cisco Small Business RV series routers allows unauthenticated remote attackers to execute arbitrary code with root privileges. It affects RV160, RV260, RV340, and RV345 routers running vulnerable firmware versions. Attackers can completely compromise affected devices to bypass authentication, run commands, and cause denial of service.

📋 TL;DR

This critical vulnerability in Cisco Small Business RV series routers allows unauthenticated remote attackers to execute arbitrary code with root privileges. It affects RV160, RV260, RV340, and RV345 routers running vulnerable firmware versions. Attackers can completely compromise affected devices to bypass authentication, run commands, and cause denial of service.

💻 Affected Systems

Products:

Cisco RV160
Cisco RV260
Cisco RV340
Cisco RV345

Versions: All versions prior to 1.0.03.22

Operating Systems: Cisco IOS-based firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations are vulnerable. No special configuration required for exploitation.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device takeover allowing attackers to intercept all network traffic, install persistent backdoors, pivot to internal networks, and render the device unusable.

🟠

Likely Case

Router compromise leading to network traffic interception, credential theft, and installation of malware for botnet participation.

🟢

If Mitigated

Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.

🌐 Internet-Facing: HIGH - Routers are typically internet-facing and the exploit requires no authentication.

🏢 Internal Only: MEDIUM - Lower risk if devices are not internet-facing, but still vulnerable to internal attackers.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: CONFIRMED

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Multiple public exploits available. ZDI-22-416 details a stack-based buffer overflow requiring no authentication.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 1.0.03.22 or later

Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-mult-vuln-KA9PK6D

Restart Required: Yes

Instructions:

1. Log into router web interface. 2. Navigate to Administration > Firmware Upgrade. 3. Download firmware 1.0.03.22 or later from Cisco website. 4. Upload and install the firmware. 5. Router will automatically reboot after installation.

🔧 Temporary Workarounds

Network Segmentation

all

Isolate routers from critical internal networks and restrict management interface access

Access Control Lists

all

Implement strict inbound firewall rules to limit access to router management interfaces

🧯 If You Can't Patch

Immediately disconnect affected routers from the internet and place behind a firewall
Implement network monitoring for unusual traffic patterns and connection attempts to router management interfaces

🔍 How to Verify

Check if Vulnerable:

Check firmware version via web interface: Administration > Firmware Upgrade or CLI: show version

Check Version:

show version

Verify Fix Applied:

Verify firmware version is 1.0.03.22 or later in Administration > Firmware Upgrade page

📡 Detection & Monitoring

Log Indicators:

Multiple failed authentication attempts followed by successful access
Unusual process execution in system logs
Configuration changes from unknown IP addresses

Network Indicators:

Unusual outbound connections from router
Traffic patterns indicating command and control communication
Port scanning originating from router

SIEM Query:

source="router_logs" AND (event_type="authentication" AND result="success" AND src_ip NOT IN [allowed_management_ips]) OR (process_name="unusual_process" AND parent_process="httpd")

📊 Metadata

CVE ID: CVE-2022-20711

CVSS v3 Score: 10.0 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CWE: CWE-121

Published: February 10, 2022

Last Updated: November 21, 2024

🔗 References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-mult-vuln-KA9PK6D Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-22-416/ Third Party Advisory,VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-mult-vuln-KA9PK6D Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-22-416/ Third Party Advisory,VDB Entry

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🔗 Related Vulnerabilities

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