CVE-2024-7828: D-Link DNS-120 Buffer Overflow Vulnerability

CVE-2024-7828 Overview

CVE-2024-7828 is a buffer overflow vulnerability affecting a broad range of end-of-life D-Link network-attached storage (NAS) devices through firmware version 20240814. The flaw resides in the cgi_set_cover function within /cgi-bin/photocenter_mgr.cgi, where the album_name argument is processed without proper bounds checking. Attackers can exploit this issue remotely with low privileges over the network, and a public disclosure has made exploit details available. D-Link confirmed the affected products are end-of-life and will not receive patches, directing customers to retire and replace the devices. The vulnerability is classified under CWE-120: Buffer Copy without Checking Size of Input.

Critical Impact

Remote attackers with low-privileged authentication can trigger a buffer overflow in the photocenter CGI handler, potentially leading to arbitrary code execution on unsupported D-Link NAS appliances that will not receive a vendor patch.

Affected Products

• D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321 (firmware up to 20240814)
• D-Link DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345 (firmware up to 20240814)
• D-Link DNS-726-4, DNS-1100-4, DNS-1200-05, DNS-1550-04 (firmware up to 20240814)

Discovery Timeline

• 2024-08-15 - CVE-2024-7828 published to the National Vulnerability Database
• 2024-08-15 - D-Link publishes Security Announcement SAP10383 confirming end-of-life status
• 2024-08-19 - Last updated in NVD database

Technical Details for CVE-2024-7828

Vulnerability Analysis

The vulnerability is a classic stack or heap buffer overflow in the cgi_set_cover function exposed by the photocenter_mgr.cgi binary. This CGI endpoint handles photo album management requests on the affected NAS devices. When a client submits a request that sets the album cover, the handler reads the album_name parameter from the HTTP request and copies it into a fixed-size buffer without validating the input length.

Because the attack vector is the network and only low-privileged credentials are required, an attacker who has obtained or guessed valid NAS credentials can reach the vulnerable endpoint and corrupt adjacent memory. Successful exploitation can crash the device, alter control flow, or enable execution of attacker-supplied shellcode within the context of the web service. Public proof-of-concept documentation is available in the BuaaIOTTeam Iot_Dlink_NAS GitHub repository.

Root Cause

The root cause is the absence of length validation on the album_name parameter before it is copied into a fixed-size destination buffer. This is a textbook instance of CWE-120, commonly introduced by use of unsafe C string functions such as strcpy or sprintf without prior length checks. The affected products are no longer maintained, so the underlying source defect will not be remediated by the vendor.

Attack Vector

An attacker reaches the vulnerable endpoint over HTTP, authenticating with any valid NAS account. The attacker then sends a crafted request to /cgi-bin/photocenter_mgr.cgi invoking the cgi_set_cover action with an oversized album_name value. The overflow corrupts memory within the CGI process and can be tuned to overwrite a saved return address or function pointer, redirecting execution. Devices exposed to the internet, or reachable through compromised internal hosts, are accessible without additional pivoting.

// Vulnerable pattern (conceptual representation based on CWE-120 and public PoC)
// No verified vendor source code is available - shown for illustration only.
POST /cgi-bin/photocenter_mgr.cgi HTTP/1.1
Host: <nas-device>
Cookie: <valid-session>
Content-Type: application/x-www-form-urlencoded

cmd=cgi_set_cover&album_name=AAAAAAAA...[oversized payload]...AAAA

Detection Methods for CVE-2024-7828

Indicators of Compromise

• HTTP POST requests to /cgi-bin/photocenter_mgr.cgi containing abnormally long album_name parameter values
• Unexpected restarts, crashes, or process respawns of the photocenter_mgr.cgi handler in NAS system logs
• New outbound connections initiated by the NAS device to unfamiliar IP addresses following CGI requests
• Unauthorized creation or modification of files in shared NAS volumes after a low-privileged login session

Detection Strategies

• Inspect web access logs and reverse-proxy telemetry for requests targeting photocenter_mgr.cgi with parameter lengths exceeding several hundred bytes.
• Deploy network intrusion detection signatures that flag oversized album_name values to known D-Link NAS CGI endpoints.
• Correlate authentication events on NAS devices with subsequent CGI requests to identify suspicious low-privileged sessions.

Monitoring Recommendations

• Forward NAS web server and authentication logs to a central SIEM for retention and correlation.
• Alert on any inbound HTTP traffic to NAS management interfaces from outside trusted administrative networks.
• Monitor outbound traffic from NAS devices for anomalous protocols, beaconing patterns, or connections to known malicious infrastructure.

How to Mitigate CVE-2024-7828

Immediate Actions Required

• Retire and replace affected D-Link NAS devices, as the vendor has confirmed these products are end-of-life and will not receive a fix.
• Remove the affected devices from any internet-facing exposure and block inbound access at the perimeter firewall.
• Rotate all credentials previously used on the affected NAS appliances, including any shared service accounts.
• Audit data stored on the NAS for integrity and migrate it to a supported storage platform.

Patch Information

No patch is available. D-Link Security Announcement SAP10383 confirms that the listed DNS, DNR, and DNS-series NAS products are end-of-life and end-of-service. The vendor recommends retirement and replacement with a currently supported product. Additional tracking is available in VulDB entry 274726.

Workarounds

• Isolate the affected NAS devices on a dedicated VLAN with no routing to user workstations or the internet.
• Restrict access to the NAS web administration interface to a small set of management IP addresses using ACLs.
• Disable the photo center or album functionality where the device configuration allows it, reducing exposure of the photocenter_mgr.cgi endpoint.
• Require VPN access for any remaining administrative interaction with the device until decommissioning is complete.

# Example: block inbound access to NAS web interface at an upstream firewall
# Replace <NAS_IP> with the affected device address
iptables -I FORWARD -p tcp -d <NAS_IP> --dport 80 -j DROP
iptables -I FORWARD -p tcp -d <NAS_IP> --dport 443 -j DROP

# Example: restrict management access to a single admin subnet
iptables -I FORWARD -p tcp -s 10.10.10.0/24 -d <NAS_IP> --dport 443 -j ACCEPT