Guidelines In DNS Security: Avoiding DNS Hijacking, Poisoning and Redirection

The importance of DNS

The Domain Name System (DNS) is a directory system which connects a website to its IP address. Your browser sends the name, the Universal Resource Locator (URL), to the DNS anytime you type the name of a location into your browser. This is regarded as a submission from a DNS.

Your browser collects the IP address of the website in response to the message - its precise numerical address on the internet. Once the IP address is on your computer, you are able to connect and connect with the web.

What is DNS Hijacking

DNS hijacking is a type of warfare that connects users to malicious pages or pop-ups using intercepted DNS queries. Not the only ones manipulating DNS are cybercriminals. In order to divert your traffic to their targets, Internet Service Providers (ISPs) even hijack your DNS.It was assumed not too long ago that DNS hijacking was a thing of the past. However, this couldn't be farther from the facts. Many corporations and organisations have been hit by DNS hijacking, including Gmail, Netflix, and PayPal.

Although all DNS hijacking functions use the same basic concept of DNS manipulation, there are minor variations in the manner in which these attacks are carried out. The address of the website we type into our browser is regarded as a completely eligible domain name (FQDN). (FQDN). You should break down this name into discernible pieces: the top-level domain (TLD), the sub-domain, and the host.

Addressing common threats to DNS security

It is possible to attack DNS in a variety of different ways. DNS DDoS, spoofing and amplification attacks are among others.

DNS DDoS

A typical example of a DDoS attack on the DNS infrastructure is the attack on Dyn. If the result of a DDoS attack on Dyn was more common, every organisation could be affected by these attacks. DNS is hierarchical, because the internal realms of an entity are managed by an internal DNS server (which can be the target of an attack).The installation of a DDoS mitigation solution is needed to defend against DNS DDoS attacks. This can screen out malicious requests while encouraging legitimate requests to proceed.

DNS spoofing

When an attacker forces a DNS server to give a wrong response to a DNS query, a DNS spoofing attack occurs, allowing them to redirect visitors to attacker-controlled pages. This offers an attacker the ability to intercept private data or try to hack bugs in the browser of the user to drop malware.

A large-scale DNS spoofing threat was revealed against Middle Eastern businesses and government entities in 2019. For these organisations, cybercriminals will exploit DNS documents and redirect them to their regulated networks. The attackers were able to decrypt and steal email and VPN credentials for these users after obtaining an SSL certificate for each domain.

DNS hijacking/redirection

When a device connects to a malicious or corrupted DNS site, DNS hijacking or redirection attacks may occur. A DNS server that offers an incorrect IP address would allow the client device to access the wrong website since the DNS server provides a translation from a domain name to an IP address.

DNS cache poisoning

This is another method for an intruder to redirect you to a "spoof" domain without your DNS requests being hijacked explicitly. Fake DNS entries are loaded into the local DNS resolver's cache (memory), redirecting you to unsafe replica sites instead of the real requested sites.

A well-planned cache poisoning attack could endanger your entire LAN and those using it because the DNS resolver handles the requests of all devices on your network. In an email or pop-up, only one user clicking a malicious connection could lead to a host of issues

Mitigating DNS spoofing

To shield against DNS hijacking attempts, both DNS server operators and users should take action. Operators on DNS should:

  • Multi-factor authentication is necessary to access DNS servers
  • Maintain patched and up-to-date DNS servers
  • Uninstalling or removing unwanted DNS server software
  • Enable DNSSEC to ensure digitally signed DNS responses

Detection of a hacked DNS server can be more difficult for DNS users. Certain best practises include:

  • Using a trustworthy, free DNS like Google Public DNS
  • Scan a domain's historical records to see if the data has been changed (may indicate a redirect attack if a record changed and it does not do so often)
  • Check the age of a certificate given and cross-check the age of a DNS record (a new certificate after a domain change may indicate exploitation of DNS redirection attack)

Amplification on DNS

In order to maximise the effect of DDoS attacks, DNS amplification attacks use DNS servers. For these attacks, DNS is useful because it uses UDP and has answers that can be far greater than the related request.An attacker sends a DNS request to a DNS server in a DNS amplification attack with the source address spoofed to that of the target computer. This question will be answered by the DNS server, sending the target a large volume of data.This can be difficult to counter DNS amplification attacks on DNS servers, since it is difficult to distinguish the genuine DNS requests of the target from spoofed attack traffic. However using tasteful packet inspection, the object of a DNS amplification attack will perform filtering that drops any inbound DNS responses for which there has not been a corresponding outbound DNS request.

References

  • Poston, H., 2020. DNS Security Best Practices: Preventing DNS Hijacking, Poisoning And Redirection - Infosec Resources. [online] Infosec Resources. Available at: .
  • Vpnmentor.com. 2020. What Is DNS Hijacking And How To Stop It | 2020 Update. [online] Available at: [Accessed 1 December 2020].

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