Facebook Google Plus Twitter LinkedIn YouTube RSS Menu Search Resource - BlogResource - WebinarResource - ReportResource - Eventicons_066 icons_067icons_068icons_069icons_070

Critical Vulnerabilities on the D-Link DIR-2640 Router

High

Synopsis

Default password on Quagga Service (CVE-2021-20132)

CVSSv3 Vector: AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (Base Score 8.8)

D-Link's DIR-2640 router, with the latest firmware (1.11B02) enables the Quagga network configuration services by default, with /sbin/zebra listening on tcp port 2601 and /sbin/ripd listening on tcp port 2602. These services are configured to use a default password for both accessing the command line interface and escalating privileges with the enable command. This password can be easily discovered, and used to gain complete control of both services, each of which are running with root privileges (that is, as the admin user, with UID 0).

Arbitrary file read and denial of service (CVE-2021-20133)

CVSSv3 Vector: AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H (Base Score 6.1)

An attacker can read a large portion of any text file on the filesystem (since the daemon runs with root privileges) by dropping into the configuration terminal interface and then setting the path for the "message of the day" banner to any file on the system. A sensitive file such as /etc/passwd can be declared the "message of the day" in this fashion, and read by the attacker when they next connect to the service.

This will set the "message of the day" banner to contents of /etc/passwd. By logging back in, the attacker can retrieve the contents of the file. Long filess may be displayed only in part, and binary data will likely be corrupted, but reasonably short text files in the ASCII encoding can be read in their entirety in this fashion.
Reading the /etc/passwd file.
If the attacker sets the "message of the day" path to a special device such as /dev/urandom, then they can bring about a denial of service to the Quagga cli interface.

Arbitrary file append (CVE-2021-20134)

CVSSv3 Vector: AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H (Base Score 8.4)

An attacker can append to any file they wish in the Quagga command line interface by, again, entering the configuration terminal and then setting the path for the log file to any file they wish on the system. They can then issue a log message with the command logmsg alerts, which will be appended to the end of that file, following a short prefix. By appending to the end of a shell script, for instance, the attacker can achieve remote code execution as root (i.e., "admin"), so long as they are able to either trigger the execution of that script, or wait until the script is executed. This technique can be used to install a backdoor on the router.
Appending to and reading from arbitrary files on the router.

Solution

This vulnerability remains unpatched at the time of writing. An intrepid user could, at their own risk, craft a shell command to disable the Quagga zebra and ripd services and then use the file-append vulnerability to write that command to the end of script that they know will be executed whenever the device is rebooted. In order for this to work, the target script would have to reside on one of the device's persistent filesystems, or the modifications would not survive a reboot. It is also possible to use the denial of service vulnerability described in the Synopsis to temporalily block access to either service.

Disclosure Timeline

September 24, 2021 - Tenable notifies D-Link of vulnerabilities and explains disclosure policy
September 24, 2021 - D-Link acknowledges notification
October 14, 2021 - D-Link requests additional details
October 14, 2021 - Tenable provides D-Link with complete proof-of-concept scripts
October 14, 2021 - D-Link acknowledges receipt of scripts
October 17, 2021 - D-Link provides Tenable with patched firmware image to review
October 26, 2021 - Tenable responds to D-Link with analysis and criticism of proposed patch, which remains vulnerable
October 27, 2021 - D-Link acknowledges receipt of feedback
December 28, 2021 - Advisory Published

All information within TRA advisories is provided “as is”, without warranty of any kind, including the implied warranties of merchantability and fitness for a particular purpose, and with no guarantee of completeness, accuracy, or timeliness. Individuals and organizations are responsible for assessing the impact of any actual or potential security vulnerability.

Tenable takes product security very seriously. If you believe you have found a vulnerability in one of our products, we ask that you please work with us to quickly resolve it in order to protect customers. Tenable believes in responding quickly to such reports, maintaining communication with researchers, and providing a solution in short order.

For more details on submitting vulnerability information, please see our Vulnerability Reporting Guidelines page.

If you have questions or corrections about this advisory, please email [email protected]

Try for free Buy now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose your subscription option:

Buy Now
Try for free Buy now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose your subscription option:

Buy Now
Try for free Buy now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose your subscription option:

Buy Now
Try for free Buy now

Try Tenable Web App Scanning

Enjoy full access to our latest web application scanning offering designed for modern applications as part of the Tenable One Exposure Management platform. Safely scan your entire online portfolio for vulnerabilities with a high degree of accuracy without heavy manual effort or disruption to critical web applications. Sign up now.

Your Tenable Web App Scanning trial also includes Tenable Vulnerability Management.

Buy Tenable Web App Scanning

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

5 FQDNs

$3,578

Buy Now

Request a demo

Tenable Security Center

Identify and prioritize vulnerabilities based on risk to your business. Managed on premises.

Request a demo

Tenable OT Security

Close OT exposure with the unified security solution for converged OT/IT environments.

Request a demo

Tenable Identity Exposure

Close identity exposure with the essential solution for the identity-intelligent enterprise.

Request a demo

Tenable Cloud Security

Close cloud exposure with the actionable cloud security platform.

Request a demo

Tenable One

The world’s leading AI-powered exposure management platform.

Request a demo

Tenable AI Exposure

See, secure, and manage how your teams use AI platforms.

Request a demo

Tenable Attack Surface Management

Gain visibility into your internet-connected assets to eliminate blind spots and unknown sources of risk.

Request a demo

Tenable Enclave Security

Know, expose and close IT and container vulnerabilities.

Try for free Buy now

Try Tenable Nessus Professional free

Tenable Nessus is the most comprehensive vulnerability scanner on the market today.

Fill out the form below to continue with a Nessus Pro trial.

Buy Tenable Nessus Professional

Tenable Nessus is the most comprehensive vulnerability scanner on the market today. Tenable Nessus Professional will help automate the vulnerability scanning process, save time in your compliance cycles and allow you to engage your IT team.

Buy a multi-year license and save. Add Advanced Support for access to phone, community and chat support 24 hours a day, 365 days a year.

Select your license

Buy a multi-year license and save.

Add support and training
Buy Now
Renew an existing license Find a reseller
Try for free Buy now

Try Tenable Nessus Professional free

Tenable Nessus is the most comprehensive vulnerability scanner on the market today.

Fill out the form below to continue with a Nessus Pro trial.

Buy Nessus Pro

Adopt the gold standard in vulnerability assessment to find and fix security gaps across your IT environment.

1 year license
$365.83
per month
Buy now for $4,390
Renew a license Find a reseller or distributor
  • Real-time vulnerability updates
  • Unlimited vulnerability scanning
  • Pre-built policies for configuration & compliance audits
  • Vulnerability scoring for prioritization
  • Configurable reports
  • Flexible deployment
Choose multi-year license and save
Save with 2 years
$8,560.50
Buy now
Save with 3 years
$12,511.50
Buy now
Try for free Buy now

Try Tenable Nessus Expert free

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Already have Tenable Nessus Professional?
Upgrade to Nessus Expert free for 7 days.

Buy Tenable Nessus Expert

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Select your license

Buy a multi-year license and save more.

Add support and training
Buy Now
Renew an existing license Find a reseller
Try for free Buy now

Try Tenable Nessus Expert free

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Already have Tenable Nessus Professional?
Upgrade to Nessus Expert free for 7 days.

Buy Nessus Expert

Expand your vulnerability assessment with advanced functionality that includes web app scanning and external attack surface discovery scanning.

1 year license
$532.50
per month
Buy now for $6,390
Renew a license Find a reseller or distributor
  • Real-time vulnerability updates
  • Unlimited vulnerability scanning
  • Web app scanning (5 FQDNs)
  • External attack surface discovery scanning (5 domains)
  • Pre-built policies for configuration & compliance audits
  • Vulnerability scoring for prioritization
  • Configurable reports
  • Flexible deployment
Choose multi-year license and save
Save with 2 years
$12,460.50
Buy now
Save with 3 years
$18,211.50
Buy now
Request a demo

Tenable Patch Management

Streamline security and IT collaboration and shorten the mean time to remediate with automation.

× Contact our sales team

Contact a sales representative