CVE-2024-7831: D-Link DNS-120 Buffer Overflow Vulnerability

CVE-2024-7831 Overview

CVE-2024-7831 is a buffer overflow vulnerability affecting a wide range of D-Link network-attached storage (NAS) products. The flaw resides in the cgi_get_cooliris function within /cgi-bin/photocenter_mgr.cgi. Attackers can manipulate the path argument to trigger a buffer overflow over the network. The exploit has been publicly disclosed. D-Link confirmed that all affected products are end-of-life and will not receive a patch. Affected devices should be retired and replaced.

Critical Impact

Remote attackers with low-privileged credentials can trigger a buffer overflow in the photo center CGI handler, leading to potential remote code execution on unsupported D-Link NAS devices.

Affected Products

• D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW (firmware up to 20240814)
• D-Link DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, 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-2024-7831 published to NVD
• 2024-08-15 - D-Link publishes Security Advisory SAP10383 confirming end-of-life status
• 2024-08-19 - Last updated in NVD database

Technical Details for CVE-2024-7831

Vulnerability Analysis

The vulnerability is a classic buffer overflow [CWE-120] in the cgi_get_cooliris function exposed by /cgi-bin/photocenter_mgr.cgi. The CGI handler processes HTTP requests for the photo center feature and copies a user-controlled path parameter into a fixed-size stack or heap buffer without proper bounds checking. An attacker supplying an oversized path value can overwrite adjacent memory, corrupt control structures, and potentially redirect execution flow.

Because the affected products are network-attached storage devices, the vulnerable CGI endpoint is typically reachable over the local network and, in misconfigured deployments, over the internet. Successful exploitation can compromise the confidentiality, integrity, and availability of data stored on the NAS.

Root Cause

The root cause is missing input length validation on the path argument before it is written to a memory buffer in cgi_get_cooliris. The CGI binary trusts attacker-supplied request data and uses unsafe string-handling routines that do not enforce destination buffer size limits. D-Link has confirmed the affected NAS products are end-of-life and will not be patched.

Attack Vector

An authenticated remote attacker with low privileges sends a crafted HTTP request to /cgi-bin/photocenter_mgr.cgi containing an oversized path parameter. The vulnerable code path inside cgi_get_cooliris copies this value into a bounded buffer, triggering memory corruption. Technical details of the request flow are documented in the public GitHub PoC writeup and the VulDB entry #274729.

Detection Methods for CVE-2024-7831

Indicators of Compromise

• HTTP requests targeting /cgi-bin/photocenter_mgr.cgi with abnormally long path query parameters or POST body values
• Unexpected crashes, restarts, or service interruptions of the photocenter_mgr.cgi process on D-Link NAS devices
• Outbound connections initiated from the NAS to unfamiliar external hosts following requests to the photo center CGI

Detection Strategies

• Inspect web server and reverse proxy logs for requests to photocenter_mgr.cgi containing path values exceeding expected length thresholds
• Deploy network intrusion detection signatures that flag oversized parameters sent to D-Link NAS administrative CGI endpoints
• Correlate authentication events with subsequent abnormal CGI requests to identify low-privileged accounts being abused

Monitoring Recommendations

• Place end-of-life NAS devices on segmented VLANs and monitor north-south traffic for anomalous outbound behavior
• Enable verbose access logging on any reverse proxy or firewall fronting the NAS web interface
• Review the D-Link advisory SAP10383 for the full list of affected models in your inventory

How to Mitigate CVE-2024-7831

Immediate Actions Required

• Retire and replace affected D-Link NAS devices, as D-Link has confirmed all listed models are end-of-life and will not receive a security patch
• Remove affected devices from public internet exposure by disabling port forwarding and WAN management access
• Restrict access to the NAS web interface to a small set of trusted internal hosts via firewall ACLs
• Rotate credentials on any account that has authenticated to an affected NAS device

Patch Information

No patch is available. D-Link confirmed in advisory SAP10383 that all affected NAS products have reached end-of-life status and will not receive firmware updates. The vendor recommends replacement with a currently supported device.

Workarounds

• Disable the photo center feature on affected NAS devices if the configuration allows it
• Block external access to /cgi-bin/photocenter_mgr.cgi at an upstream firewall or reverse proxy
• Migrate stored data to a supported storage platform and decommission affected D-Link NAS hardware

# Example firewall rule to block external access to the vulnerable CGI endpoint
# (adjust interface and NAS IP for your environment)
iptables -A FORWARD -p tcp -d <NAS_IP> --dport 80 \
  -m string --string "/cgi-bin/photocenter_mgr.cgi" --algo bm -j DROP
iptables -A FORWARD -p tcp -d <NAS_IP> --dport 443 \
  -m string --string "/cgi-bin/photocenter_mgr.cgi" --algo bm -j DROP