CVE-2011-4723: D-Link DIR-300 Router Cleartext Storage of a Password Vulnerability

Overview

CVE-2011-4723 is a vulnerability in the D-Link DIR-300 router in which passwords are stored in cleartext. An attacker who can reach the stored credentials can obtain sensitive information without needing to break encryption. Because this device is a network gateway, exposure of those credentials can lead to unauthorized access to the router itself or to services that reuse the same passwords.

CISA notes that the impacted product is end-of-life and should be disconnected if still in use. Confirm all technical details against the vendor advisory before acting.

How it works

The weakness is classified under CWE-310 (cryptographic issues). In this case the concrete problem is cleartext storage of a password: the router keeps credential material in a form that is readable once an attacker gains access to the storage location or to a configuration export that contains it.

A context-dependent attacker who can read the relevant storage—through local access, a compromised management interface, a backup file, or another path that yields the configuration—can simply retrieve the password. No cryptographic attack is required. The obtained credentials can then be reused against the router’s administrative interfaces or against other systems if the same password was reused elsewhere. Exact storage locations and access methods are not detailed in the provided facts; treat any claim of a specific exploit path as something that must be verified against the vendor advisory.

Am I affected? How to find it in your systems

The D-Link DIR-300 is a consumer and small-office wireless router. It typically appears at the network edge as the default gateway, DHCP server, and Wi-Fi access point. Inventory steps:

• Check physical devices and asset records for the model string “DIR-300”.
• Review DHCP client lists, ARP tables, and network-management inventories for the device’s MAC OUI and hostname patterns associated with D-Link.
• Inspect router management pages or configuration backups for the model and firmware identifiers; compare them with the vendor advisory to confirm whether the cleartext-storage issue applies.
• Search configuration repositories, backup shares, and ticket systems for exported DIR-300 configs that may contain readable credentials.

Telemetry signs of exploitation are generic for this class: unexpected administrative logins, configuration changes, or outbound connections originating from the router after an unexplained credential use. Because the product is end-of-life, any still-running unit should be treated as high risk regardless of observed exploitation.

How to remediate

The primary remediation stated by CISA is to disconnect the device: the product is end-of-life and should no longer be used. If a supported replacement is available from the vendor, migrate services to that platform and apply the current vendor-recommended firmware and configuration hardening.

After removal or replacement:

• Change every password that was ever stored on or used with the DIR-300, including the router admin password, Wi-Fi PSKs, and any upstream or service accounts that may have been entered into the device.
• Invalidate any exported configuration files that contain cleartext credentials and purge them from backups once a secure replacement config exists.
• Re-baseline network segmentation so that the new gateway does not inherit overly permissive rules from the old device.

Confirm the exact replacement and any residual configuration guidance against the vendor advisory.

If you can't patch immediately

Because the product is end-of-life, “patching” is not a realistic long-term option. Until the device can be removed:

• Isolate it on a dedicated network segment with strict firewall rules that limit management access to a small set of trusted administrative hosts.
• Disable remote administration and any unnecessary services (WAN-side management, UPnP, etc.) if the interface still allows it.
• Place a monitoring or virtual-patching control (for example a network IDS/IPS or reverse-proxy WAF in front of any exposed management path) to alert on or block anomalous access attempts.
• Continuously monitor authentication logs and configuration integrity; treat any unexplained change as a potential credential compromise.
• Plan and execute decommissioning as soon as possible—compensating controls only reduce, not eliminate, risk for an unmaintained device that stores passwords in cleartext.

If your data may have been exposed

Actively exploited vulnerabilities on network devices frequently lead to broader breaches once credentials are obtained. If the DIR-300 was reachable by untrusted parties or if configuration backups left the organization, assume the stored passwords may have been read. Rotate all related credentials, review logs for lateral movement, and consider whether other systems reused the same secrets. You can run a free exposure scan of your email addresses against known breach data sets to check whether those identities appear in public breach corpora.