D-Link End-of-Life (EOL) NAS Devices Remote Code Execution and Backdoor Vulnerability (CVE-2024-3273) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTAll firmware versions of End-of-Life (EOL) D-Link NAS models DNS-320L, DNS-325, DNS-327L, and DNS-340L
Unauthenticated remote attackers can leverage hardcoded credentials and inject arbitrary system commands to achieve full system compromise
Since these products are no longer supported, it is strongly recommended to immediately retire and replace the affected devices
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
No official patches or firmware updates are available from D-Link as these products have reached End-of-Life (EOL) status. The only effective remediation is to decommission the devices and replace them with supported models.
2. Temporary Workaround & Hardening Configuration
If immediate replacement is not possible, isolate the NAS from the internet. Block all inbound traffic to the NAS web interface using network firewalls or local iptables rules.
# Block all external HTTP/HTTPS traffic to the NAS IP (e.g., 192.168.1.100)
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.100 -p tcp --dport 443 -j DROP
# Restrict access to a trusted management IP only (e.g., 192.168.1.50)
iptables -A INPUT -s 192.168.1.50 -d 192.168.1.100 -p tcp --dport 80 -j ACCEPT3. Log Audit & IoC Verification Commands
Inspect web server access logs for unauthorized access attempts targeting the vulnerable CGI script and the hardcoded user account.
# Search web access logs for requests targeting the vulnerable CGI script
grep -i 'nas_sharing.cgi' /var/log/httpd/access_log /var/log/nginx/access.log 2>/dev/null
# Check for the presence of the hardcoded user 'messagebus' or command execution parameters
egrep -i 'user=messagebus|system=' /var/log/httpd/access_log 2>/dev/nullStop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2024-3273) is a critical security flaw discovered in legacy D-Link Network Attached Storage (NAS) devices. The root cause lies within the HTTP GET Request Handler of the /cgi-bin/nas_sharing.cgi script. The application fails to properly sanitize user-supplied input in the system parameter and contains hardcoded credentials (username 'messagebus' with an empty password), leading to an authentication bypass and subsequent command injection (CWE-77).
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by sending a crafted HTTP GET request to the /cgi-bin/nas_sharing.cgi endpoint. By supplying user=messagebus and an empty password, the attacker bypasses authentication. The attacker then appends arbitrary shell commands to the system or cmd parameter. The web server executes these commands with elevated privileges (typically root), allowing the attacker to download malware, establish a reverse shell, or join the device to a botnet.
3. Infrastructure & Business Impact
With a CVSS score of 9.8 (Critical) and its inclusion in the CISA KEV catalog, this vulnerability poses an immediate threat. Successful exploitation allows complete compromise of the NAS device, potentially leading to data exfiltration, ransomware deployment, and lateral movement within the internal network. Because these devices are EOL, no official security patches will be released, making them permanent targets for automated exploitation campaigns.
Official Vendor Advisories & References
** UNSUPPORTED WHEN ASSIGNED ** A vulnerability, which was classified as critical, was found in D-Link DNS-320L, DNS-325, DNS-327L and DNS-340L up to 20240403. Affected is an unknown function of the file /cgi-bin/nas_sharing.cgi of the component HTTP GET Request Handler. The manipulation of the argument system leads to command injection. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-259284. NOTE: This vulnerability only affects products that are no longer supported by the maintainer. NOTE: Vendor was contacted early and confirmed immediately that the product is end-of-life. It should be retired and replaced.
Frequently Asked SecOps Questions (CVE-2024-3273)
FAQQ1. How critical is CVE-2024-3273 and is it actively exploited in the wild?
CVE-2024-3273 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 100.0%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2024-3273?
Primary impacted vendors include d-link across dns-320l, dns-325, dns-327l, dns-340l. Scope summary: D-Link DNS-320L, DNS-325, DNS-327L, DNS-340L (All firmware versions - End-of-Life)
Q3. What temporary mitigations or workarounds exist for CVE-2024-3273 before patching?
[Mitigation] Since these products are no longer supported, it is strongly recommended to immediately retire and replace the affected devices Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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