Hackers employ DNS for various purposes like redirecting traffic to enable man-in-the-middle attacks, infecting malware through harmful sites, and flooding DNS servers with fake requests such as DDoS.
DNS is everywhere and is a basic part of internet communication, making it an attractive target for threat actors.
One thing that is quite clear is that incorporating Dynamic DNS (DDNS) services into vendor appliances like those made by Fortinet or QNAP has many cybersecurity risks.
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To make customer devices easier to find, it presents a perfect scenario for attackers who may use this information to accurately identify and attack such devices that might be exposed to known vulnerabilities or zero-days targeting the specific vendors’ products.
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Technical Analysis
This conjunction between DDNS and TLS implementations inadvertently allows threat actors to scale up their exploitation of these flaws, which increases the overall security risk customers face when they employ these in-built services.
Web security requires the use of Public Key Infrastructure, which is implemented by X. 509 certificates, and the use of encrypted connections through Transport Layer Security or Secure Socket Layer.
Certificate Transparency (CT) focuses on preventing the issuing of deceptive certificates by logging all certificates off the public registry.
However, the presence of this public CT log also unveils subdomains and fully qualified domain names (FQDNs) to the global map, making it rather easy for attackers to map an organization’s attack surface and identify a number of attack vectors based on this blunder.
The concern here is the transparency mechanism aimed at increasing security opens a door for improving insecurity.
DDNS is the technology used to translate ever-changing IP addresses to domain names. It may be installed as part of vendor appliances for remote connection.
Still, this experiment, when combined with automated certificate issuance for these proprietary DDNS domains, has the opposite outcome and reveals the vendor’s customer base.
Independent of any port scans or network reconnaissance, attackers can search for the vendor’s DDNS domain in Certificate Transparency logs and obtain thousands of potential targets.
For instance, search results indicate that over 2300 devices using Fortinet FortiGate firewalls incorporate the servers’ fortiddns.com domain and 4,400 QNAP NAS devices myQNAPcloud. opt, and 1300 at Mikrotik routers or switches at serialnumber.sn.mynetname.net domains.
DDNS and certificate transparency have made the exploitation of vulnerabilities in the vendor’s product range almost common due to unintended information disclosure.
While convenient, integrating DDNS capabilities and automated certificate provisioning in vendor appliances inadvertently encourages the exposure of administrative interfaces to the Internet.
This combination naturally discloses information attackers can exploit to identify and target vulnerable devices at scale.
It is imperative that manufacturers explicitly communicate these security risks to customers, strongly emphasizing the need for cautious configuration to mitigate potential exploitation arising from this unintended information disclosure.
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