CVE-2024-6525: D-Link DAR-7000 Firmware RCE Vulnerability

CVE-2024-6525 Overview

CVE-2024-6525 is a deserialization vulnerability in D-Link DAR-7000 devices running firmware up to version 20230922. The flaw resides in the /log/decodmail.php script, where the file parameter is passed to a deserialization routine without proper validation. An authenticated remote attacker with high privileges can manipulate this parameter to trigger unsafe object deserialization [CWE-502]. The exploit has been publicly disclosed and referenced under VulDB ID VDB-270368. D-Link has confirmed that the DAR-7000 product line is end-of-life and no longer receives security updates from the vendor.

Critical Impact
Authenticated attackers can trigger PHP object deserialization on the affected appliance through a network-reachable endpoint, and the device is unsupported by D-Link.

Affected Products

D-Link DAR-7000 hardware appliance (all hardware revisions)
D-Link DAR-7000 firmware versions up to and including 20230922
End-of-life D-Link DAR-7000 deployments no longer receiving vendor patches

Discovery Timeline

2024-07-05 - CVE-2024-6525 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-6525

Vulnerability Analysis

The vulnerability is a PHP insecure deserialization issue located in the /log/decodmail.php script of the D-Link DAR-7000 web management interface. The file request parameter flows into a deserialization function without input sanitization or type restrictions. When an attacker submits a crafted serialized PHP object, the interpreter reconstructs it and invokes magic methods such as __wakeup or __destruct on attacker-controlled data. This behavior enables object injection against classes present in the application runtime.

Exploitation requires network access to the appliance's management interface and valid credentials with elevated privileges. The vulnerability is classified under CWE-502: Deserialization of Untrusted Data. Because the DAR-7000 line is designated end-of-life, D-Link has published security advisory SAP10354 notifying customers that no firmware fix will be released.

Root Cause

The root cause is the use of PHP's native deserialization on attacker-controlled input passed through the file HTTP parameter to /log/decodmail.php. The script does not validate the parameter as a safe file identifier or restrict allowed classes before invoking deserialization logic. Any class loaded in scope with side-effect-bearing magic methods becomes a potential exploitation gadget.

Attack Vector

The attack vector is remote and network-based, delivered through HTTP requests to the appliance's management interface. An attacker sends a request to /log/decodmail.php containing a serialized PHP object in the file parameter. The vulnerability requires high privileges, meaning the attacker must already possess valid administrative credentials. Successful exploitation can result in the execution of gadget chains available in the underlying PHP code, and public proof-of-concept material describes reaching remote code execution on the appliance.

The vulnerability mechanism is documented in the public writeup referenced from the GitHub PoC Repository. No verified code snippet is reproduced here; refer to the linked advisory and PoC repository for exploitation details.

Detection Methods for CVE-2024-6525

Indicators of Compromise

HTTP requests to /log/decodmail.php containing a file parameter whose value begins with PHP serialization prefixes such as O:, a:, or s:.
Unusual outbound connections initiated by the DAR-7000 appliance immediately after requests to decodmail.php.
Web server or PHP error log entries referencing unserialize() failures, unknown class instantiations, or unexpected __wakeup invocations.
New or modified files, cron entries, or shell processes appearing on the appliance after management-plane activity.

Detection Strategies

Deploy network intrusion detection signatures that inspect HTTP request bodies destined for the DAR-7000 management interface for PHP serialization markers.
Monitor authentication logs on the appliance for administrative logins followed by requests to /log/decodmail.php.
Correlate web access logs with process-execution telemetry from adjacent systems to identify lateral movement originating from the appliance.

Monitoring Recommendations

Forward the appliance's HTTP access logs and system logs to a centralized SIEM or data lake for retention and correlation.
Alert on any access to /log/ endpoints from source addresses outside a defined administrative allowlist.
Baseline outbound network traffic from the DAR-7000 and flag deviations that could indicate a reverse shell or callback.

How to Mitigate CVE-2024-6525

Immediate Actions Required

Retire and replace D-Link DAR-7000 appliances, as the product is end-of-life and will not receive a vendor patch per D-Link advisory SAP10354.
Remove the management interface from any network segment reachable by untrusted users or the internet.
Rotate all administrative credentials used on the appliance and audit account inventory for unused or shared accounts.
Review appliance configuration and logs for signs of prior exploitation before decommissioning.

Patch Information

No security patch is available. D-Link's Security Advisory SAP10354 confirms that the DAR-7000 has reached end-of-life status and recommends that customers migrate to a supported product. Continued use of the device leaves the deserialization flaw permanently exposed.

Workarounds

Restrict access to the management interface using upstream firewall rules that permit only a small set of jump-host IP addresses.
Place the appliance behind a reverse proxy or web application firewall configured to block requests to /log/decodmail.php and to inspect for PHP serialization payloads in request parameters.
Enforce network segmentation so that the appliance cannot initiate outbound connections to arbitrary destinations.
Plan and execute migration to a supported next-generation appliance from a vendor providing active security maintenance.

bash

# Example upstream firewall restriction (iptables)
# Allow management access only from a defined admin subnet
iptables -A FORWARD -p tcp -s 10.10.20.0/24 -d <DAR-7000-IP> --dport 443 -j ACCEPT
iptables -A FORWARD -p tcp -d <DAR-7000-IP> --dport 443 -j DROP

# Example WAF rule concept (ModSecurity)
SecRule REQUEST_URI "@contains /log/decodmail.php" \
  "id:1006525,phase:2,deny,status:403,\
   msg:'Block D-Link DAR-7000 decodmail.php (CVE-2024-6525)'"
SecRule ARGS:file "@rx ^(O|a|s):[0-9]+:" \
  "id:1006526,phase:2,deny,status:403,\
   msg:'Blocked PHP serialized payload in file parameter'"