CVE-2024-7830: D-Link DNS-120 Buffer Overflow Vulnerability

CVE-2024-7830 Overview

CVE-2024-7830 is a buffer overflow vulnerability affecting a broad range of D-Link network-attached storage (NAS) devices that have reached end-of-life status. The flaw resides in the cgi_move_photo function within /cgi-bin/photocenter_mgr.cgi, where the photo_name argument is processed without proper bounds checking [CWE-120]. Attackers can exploit the vulnerability remotely over the network with low privileges. D-Link confirmed the affected products are no longer supported and recommends retirement and replacement rather than patching. Exploit details have been disclosed publicly, increasing the risk to exposed devices.

Critical Impact

Remote attackers with low-privileged authenticated access can trigger a buffer overflow in the photocenter_mgr.cgi handler, potentially leading to arbitrary code execution on unsupported D-Link NAS devices.

Affected Products

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

Discovery Timeline

• 2024-08-15 - CVE-2024-7830 published to NVD
• 2024-08-19 - Last updated in NVD database

Technical Details for CVE-2024-7830

Vulnerability Analysis

The vulnerability exists in the cgi_move_photo function of the /cgi-bin/photocenter_mgr.cgi binary, which handles photo management operations on D-Link NAS devices. The function accepts a photo_name parameter from HTTP requests and copies it into a fixed-size stack or heap buffer without validating the input length. This classic memory safety failure [CWE-120] allows attackers to overflow adjacent memory regions.

Successful exploitation can corrupt control structures such as return addresses or function pointers. On these embedded MIPS and ARM-based NAS devices, exploit mitigations like Address Space Layout Randomization (ASLR) and stack canaries are typically absent or weak, simplifying reliable exploitation. Because D-Link has classified all affected devices as end-of-life, no firmware patch will be released.

Root Cause

The root cause is missing input length validation in the cgi_move_photo handler before the photo_name argument is processed into an internal buffer. The CGI program trusts client-supplied parameters without enforcing bounds, a pattern common in legacy embedded web interfaces.

Attack Vector

The attack is delivered over the network through an HTTP request to the /cgi-bin/photocenter_mgr.cgi endpoint with an oversized photo_name value. The attacker requires low-privileged authentication, but devices exposed to the internet or untrusted networks are at elevated risk. Public disclosure of the exploit on a GitHub proof-of-concept repository lowers the technical barrier for adversaries.

No verified code examples are reproduced here. Technical exploitation details are available in the GitHub PoC Repository and the D-Link Security Advisory SAP10383.

Detection Methods for CVE-2024-7830

Indicators of Compromise

• HTTP POST or GET requests to /cgi-bin/photocenter_mgr.cgi containing abnormally long photo_name parameters
• Unexpected crashes, restarts, or service interruptions of the photocenter CGI process on D-Link NAS devices
• Outbound connections from NAS devices to unknown hosts following web interface activity
• New or modified files in NAS shares that do not correspond to authorized user activity

Detection Strategies

• Inspect web server and proxy logs for requests targeting photocenter_mgr.cgi with parameter values exceeding expected lengths
• Deploy network intrusion detection signatures that match oversized photo_name arguments in HTTP traffic to D-Link NAS management interfaces
• Conduct network discovery scans to identify end-of-life D-Link NAS appliances still in production

Monitoring Recommendations

• Forward NAS device access logs and network flow data to a centralized SIEM or data lake for correlation against known exploitation patterns
• Alert on any inbound connection attempts to NAS management ports from untrusted network segments
• Track process and service availability on affected devices to detect crash-driven exploitation attempts

How to Mitigate CVE-2024-7830

Immediate Actions Required

• Retire and replace all affected D-Link NAS devices, as instructed by the vendor in advisory SAP10383
• Remove affected NAS devices from internet exposure and restrict access to a trusted management VLAN
• Disable the photo center feature if it is not required for business operations
• Rotate credentials for any accounts that have authenticated to the affected NAS devices

Patch Information

No patch is available. D-Link has confirmed the affected products are end-of-life and unsupported. The vendor recommends device retirement per the D-Link Security Advisory SAP10383.

Workarounds

• Place affected NAS devices behind a firewall and block all inbound access to /cgi-bin/photocenter_mgr.cgi from untrusted networks
• Restrict NAS web interface access to specific administrative IP addresses using access control lists
• Migrate stored data to a supported storage platform and decommission the legacy NAS hardware

# Example firewall rule to restrict NAS web interface access
iptables -A INPUT -p tcp --dport 80 -s <trusted_admin_subnet> -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s <trusted_admin_subnet> -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP