CVE-2024-7829: D-Link DNS-120 Buffer Overflow Vulnerability

CVE-2024-7829 Overview

CVE-2024-7829 is a buffer overflow vulnerability affecting more than 20 end-of-life D-Link network attached storage (NAS) and network video recorder products. The flaw resides in the cgi_del_photo function of /cgi-bin/photocenter_mgr.cgi, where the current_path argument is processed without proper bounds checking [CWE-120]. Attackers can trigger the overflow remotely over the network to compromise confidentiality, integrity, and availability of affected devices. D-Link has confirmed these products are end-of-life and will not receive a patch. Public exploit details have been disclosed, increasing the risk of opportunistic attacks against exposed devices.

Critical Impact

Remote attackers with low privileges can trigger a buffer overflow in the cgi_del_photo CGI handler to corrupt memory on unsupported D-Link NAS devices, with public exploit details already disclosed.

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-2024-7829 published to NVD
• 2024-08-19 - Last updated in NVD database

Technical Details for CVE-2024-7829

Vulnerability Analysis

The vulnerability is a classic stack/heap buffer overflow [CWE-120] in the cgi_del_photo function exposed by the photocenter_mgr.cgi binary. This CGI endpoint handles photo deletion operations within the NAS web management interface. The handler reads the current_path parameter from an attacker-controlled HTTP request and copies it into a fixed-size buffer without validating the input length.

Because the affected firmware ships in dozens of legacy D-Link NAS and NVR appliances, the attack surface is wide. The vendor was contacted and confirmed the products are end-of-life. No firmware fix will be issued, leaving exploitation as a permanent risk for any device that remains connected. The proof of concept published by the BuaaIOTTeam demonstrates the overflow path against current_path.

Root Cause

The root cause is missing bounds checking on the current_path HTTP parameter before it is written into a fixed-size buffer inside cgi_del_photo. The CGI binary relies on unsafe string handling routines and trusts attacker-supplied length, which violates secure coding practices for embedded web interfaces.

Attack Vector

The attack is network-reachable and requires low privileges, meaning an authenticated session on the management interface is needed. Attackers send a crafted HTTP request to /cgi-bin/photocenter_mgr.cgi with an oversized current_path value targeting the cgi_del_photo action. The resulting memory corruption can crash the service or, depending on the firmware build, enable arbitrary code execution under the web service context. Refer to the GitHub PoC Repository for the disclosed request pattern.

Detection Methods for CVE-2024-7829

Indicators of Compromise

• Unexpected HTTP POST or GET requests to /cgi-bin/photocenter_mgr.cgi containing abnormally long current_path parameter values.
• Repeated crashes, reboots, or service restarts of the NAS web management daemon following photo center requests.
• Outbound connections initiated by the NAS to unknown hosts after web interface activity, indicating possible post-exploitation.

Detection Strategies

• Inspect web access logs on affected devices for requests to photocenter_mgr.cgi with current_path values exceeding typical filesystem path lengths.
• Deploy network intrusion detection signatures that flag oversized HTTP parameters destined for legacy D-Link NAS management ports.
• Correlate authentication events with subsequent CGI requests to identify low-privileged accounts probing the photo center endpoint.

Monitoring Recommendations

• Monitor north-south and east-west traffic to D-Link NAS management interfaces and alert on any external exposure of administrative ports.
• Capture and retain HTTP request bodies destined for /cgi-bin/ paths on legacy storage appliances for forensic review.
• Track device health metrics for unexplained CPU spikes or process restarts that may indicate exploitation attempts.

How to Mitigate CVE-2024-7829

Immediate Actions Required

• Retire and replace all affected D-Link NAS and NVR models, as the vendor has confirmed end-of-life status and no patch will be released.
• Remove affected devices from internet exposure immediately by blocking inbound access at the perimeter firewall.
• Rotate any credentials previously used to administer the affected appliances, since low-privileged accounts can trigger the flaw.

Patch Information

No patch is available. D-Link confirmed in Security Advisory SAP10383 that the affected DNS, DNR, and related NAS product lines are end-of-life and out of support. The vendor recommends decommissioning and replacing the hardware.

Workarounds

• Isolate affected NAS devices on a dedicated management VLAN with strict access control lists permitting only trusted administrative hosts.
• Disable the photo center feature and the web management interface where the firmware allows, or restrict it to loopback access via reverse proxy.
• Migrate stored data to a supported storage platform and power off legacy D-Link NAS units once migration is complete.

# Example perimeter ACL to block external access to legacy D-Link NAS web management
iptables -A INPUT -p tcp --dport 80 -s 0.0.0.0/0 -d <nas-ip> -j DROP
iptables -A INPUT -p tcp --dport 443 -s 0.0.0.0/0 -d <nas-ip> -j DROP
# Allow only the management subnet
iptables -I INPUT -p tcp --dport 443 -s 10.10.20.0/24 -d <nas-ip> -j ACCEPT