CVE-2019-1620 – CVE-2019-1620 is a critical vulnerability in Ci... (How to Fix)

Q: What is the severity of CVE-2019-1620?

CVE-2019-1620 has a CVSS score of 9.8 (CRITICAL). CVE-2019-1620 is a critical vulnerability in Cisco Data Center Network Manager (DCNM) that allows unauthenticated remote attackers to upload arbitrary files and execute code with root privileges. This affects DCNM web management interfaces exposed to networks. Organizations using vulnerable DCNM versions are at immediate risk of complete system compromise.

📋 TL;DR

CVE-2019-1620 is a critical vulnerability in Cisco Data Center Network Manager (DCNM) that allows unauthenticated remote attackers to upload arbitrary files and execute code with root privileges. This affects DCNM web management interfaces exposed to networks. Organizations using vulnerable DCNM versions are at immediate risk of complete system compromise.

💻 Affected Systems

Products:

Cisco Data Center Network Manager (DCNM)

Versions: Versions prior to 11.2(1)

Operating Systems: Linux (DCNM appliance)

Default Config Vulnerable: ⚠️ Yes

Notes: All DCNM deployments with web management interface enabled are vulnerable. The vulnerability exists in the default configuration.

📦 What is this software?

Data Center Network Manager by Cisco

View all CVEs affecting Data Center Network Manager →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system takeover with root privileges, data exfiltration, lateral movement to connected systems, and persistent backdoor installation.

🟠

Likely Case

Remote code execution leading to data theft, service disruption, and deployment of ransomware or cryptocurrency miners.

🟢

If Mitigated

Limited impact if properly segmented and monitored, but still potential for initial foothold in network.

🌐 Internet-Facing: HIGH - Unauthenticated remote exploit allows attackers from anywhere on the internet to compromise vulnerable systems.

🏢 Internal Only: HIGH - Even internally, any user on the network could exploit this without credentials.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: CONFIRMED

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Multiple public exploit scripts are available. The vulnerability is trivial to exploit with readily available tools.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 11.2(1) and later

Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190626-dcnm-file-upload

Restart Required: Yes

Instructions:

1. Download DCNM version 11.2(1) or later from Cisco Software Center. 2. Backup current configuration. 3. Install the update following Cisco's upgrade guide. 4. Restart the DCNM service or appliance.

🔧 Temporary Workarounds

Restrict Network Access

linux

Limit access to DCNM web interface to trusted IP addresses only using firewall rules.

iptables -A INPUT -p tcp --dport 443 -s trusted_ip_range -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

Disable Web Interface

linux

Temporarily disable the web management interface if not required for operations.

systemctl stop tomcat
systemctl disable tomcat

🧯 If You Can't Patch

Isolate DCNM appliance on a dedicated VLAN with strict firewall rules allowing only necessary management traffic
Implement network-based intrusion detection rules to detect exploitation attempts and file upload patterns

🔍 How to Verify

Check if Vulnerable:

Check DCNM version via web interface or SSH: cat /opt/cisco/dcnm/version.txt | grep 'DCNM Version'

Check Version:

cat /opt/cisco/dcnm/version.txt | grep 'DCNM Version'

Verify Fix Applied:

Verify version is 11.2(1) or later and test that unauthorized file upload attempts are blocked

📡 Detection & Monitoring

Log Indicators:

Unusual file uploads to DCNM web directories
Multiple failed authentication attempts followed by successful file upload
Suspicious POST requests to upload endpoints

Network Indicators:

HTTP POST requests to /upload endpoints from unexpected sources
Outbound connections from DCNM to suspicious external IPs

SIEM Query:

source="dcnm.logs" AND (url="*upload*" OR method="POST") AND status=200 AND user="-"

📊 Metadata

CVE ID: CVE-2019-1620

CVSS v3 Score: 9.8 (CRITICAL)

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

CWE: CWE-264

Published: June 27, 2019

Last Updated: November 21, 2024

🔗 References

http://packetstormsecurity.com/files/153546/Cisco-Data-Center-Network-Manager-11.1-1-Remote-Code-Execution.html Third Party Advisory,VDB Entry
http://packetstormsecurity.com/files/154304/Cisco-Data-Center-Network-Manager-Unauthenticated-Remote-Code-Execution.html Third Party Advisory,VDB Entry
http://seclists.org/fulldisclosure/2019/Jul/7 Mailing List,Third Party Advisory
http://www.securityfocus.com/bid/108906 Third Party Advisory,VDB Entry
https://seclists.org/bugtraq/2019/Jul/11 Mailing List,Third Party Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190626-dcnm-codex Vendor Advisory
http://packetstormsecurity.com/files/153546/Cisco-Data-Center-Network-Manager-11.1-1-Remote-Code-Execution.html Third Party Advisory,VDB Entry
http://packetstormsecurity.com/files/154304/Cisco-Data-Center-Network-Manager-Unauthenticated-Remote-Code-Execution.html Third Party Advisory,VDB Entry
http://seclists.org/fulldisclosure/2019/Jul/7 Mailing List,Third Party Advisory
http://www.securityfocus.com/bid/108906 Third Party Advisory,VDB Entry
https://seclists.org/bugtraq/2019/Jul/11 Mailing List,Third Party Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190626-dcnm-codex Vendor Advisory

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🔗 Related Vulnerabilities

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