That way, you can direct someone to the IP address specified in the file on that person’s machine. Unfortunately, changing the contents of a single file on many devices can be too difficult a task. That’s why attackers focus on changing what’s on the DNS server. Thus, there is no need to make changes on the client side. Instead, make one change on the DNS server, and now the answer to all those clients will be updated to reflect what the attacker has changed. Although there are enough ways to do this, most involve taking control of the DNS server.

What is a DNS and DNS Server?

First, let’s remember What DNS is? It is a “domain name system,” and to fully understand it, it is essential to clarify some of the related terms.

How DNS works?

When you write the domain name of a website, the following process occurs:

The DNS lookup process is a vital structure used throughout the Internet. Unfortunately, criminals can abuse vulnerabilities in DNS, so you need to be aware of possible redirects.

DNS Hijacking

DNS hijacking is probably a general term that encompasses the other methods. DNS hijacking can be considered any attack that tricks an end user (exactly, his computer) into thinking it is interacting with a legitimate domain name. Instead, however, it interacts with a domain name or IP address set by an attacker. This is sometimes referred to as DNS redirection.

There are many ways to hijack DNS, but not all are illegal. For example, the most common method we see is used by an authorized portal, such as a pay-per-use WiFi access point: before the user pays for access, the access point service intercepts all DNS requests and, regardless of what has been set, it returns the page of the payment server so that the user can purchase WiFi access.

Changing the client device settings to a different DNS server is another standard attack method. An attacker can change a user’s DNS settings so that instead of 8.8.8.8, it uses the IP address of the DNS server under the attacker’s control. When the user requests an online banking website, the rogue DNS server can return an IP address outwardly disguised as the target website. It can act as a proxy to capture all the data sent to the website. This is what the DNSChanger trojan/malware does – fortunately, it is pretty rare these days.

Another way to gain unauthorized access to authoritative DNS data, exploit a DNS login system vulnerability or use some other tricky method. Some attacks are based on the fact that certain domains look identical in different fonts or encodings (homograph attack). One of the first phishing attempts was using the domain name paypaI.com. The attacker then registered the domain name and wrote the letter i in uppercase to make it look like a lowercase L. That way, many people thought it was the real PayPal.com. Now that the DNS supports international characters, it’s even harder to tell the difference between terms with the exact spelling.

DNS Spoofing

DNS spoofing also refers to any attack that tries to change the DNS records returned to the requester to a response chosen by the attacker. This can include some techniques such as using cache poisoning or some type of man-in-the-middle attack. We sometimes use the terms “DNS hijacking” and “DNS spoofing” as synonyms. This method is also widely used by paid Wi-Fi access points in airports and hotels. In some cases, network security groups can use it as a quarantine tool to isolate an infected device.

DNS Spoofing VS DNS Hijacking

Although DNS spoofing is often confused with DNS hijacking because both occur at the local system level, they are two different types of attacks. In most cases, DNS spoofing or cache poisoning simply involves overwriting the local DNS cache values with fake ones to redirect the victim to a malicious website. On the other hand, DNS hijacking (also known as DNS redirection) often involves malware infection to hijack this critical system service. In this case, malware hosted on the local computer can change the TCP/IP configuration to point to a malicious DNS server, eventually redirecting traffic to the phishing website.

Conclusion

As you can see, DNS is critical to the day-to-day operation of websites and online services. Unfortunately, attackers may see it as an attractive opportunity to attack your networks. This is why monitoring your DNS servers and traffic is crucial. We must be careful where we go on the Internet and what emails we open. Even the slightest difference, for example, the absence of an SSL certificate, is a signal to check the website you want to visit.

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What is a DNS Server?

DNS means “domain name system”. But before we explain DNS servers, it is essential to clarify the terms related to this topic. Now that we’ve established the definition of DNS and have a basic understanding of DNS let’s understand how DNS lookups work.

How Does DNS Lookup Work?

The process of finding a site by domain name works as follows:

1. Your web browser tries to recall the IP address associated with the domain name. If this site has been visited, the IP address may be stored in the local memory cache and recalled from there.
2. The process continues until one of the components finds out where the destination IP address is.
3. The browser requests a resolving name server to retrieve the IP address. This request searches through the chain of servers to find the appropriate IP address for the domain.
4. Eventually, the resolver finds and relays the IP address to the server, which forwards it back to the web browser.

The DNS lookup process is an integral part used throughout the Internet. Unfortunately, criminals can take advantage of vulnerabilities in DNS, so you need to be aware of possible redirects. First, let’s clarify what DNS spoofing is and how it works.

How DNS Cache Poisoning and Spoofing Works?

Here are the two most common variants of DNS attacks:

Methods of DNS spoofing and Cache Poisoning Attacks

Here are the most common methods of DNS attacks:

Risks of DNS Poisoning and Spoofing

DNS spoofing has some risks, which can put your devices and data at risk. Listed below are the risks of poisoning and DNS spoofing:

1. Personal data theft can be incredibly lucrative for attackers using DNS spoofing. Banking websites and famous online stores are easy to spoof, meaning any password, credit card information, or personal information can be compromised. Redirects will be to phishing websites designed to collect your data.
2. Malware infection is another common threat of DNS spoofing. The destination may turn out to be a fake site containing viruses. Drive-by Downloads are an easy way to automate infection of your system. As a result, if you do not use protection, you are exposed to risks such as spyware, keyloggers, or worms.
3. A fake DNS can cause your security updates to stop. If fake sites include Internet security vendors, legitimate security updates will not be performed. As a result, the device may be exposed to additional threats such as viruses or Trojans.
4. Censorship is a risk that is common in some countries. For example, China uses DNS modifications to ensure that all Websites viewed in the country are filtered. This national-level block, known as the Great Firewall, is one example of how powerful DNS spoofing can be.
5. It’s pretty difficult to eliminate the effects of DNS cache poisoning. Because clearing an infected server doesn’t get rid of the problem on a desktop or mobile device, the device will return to the spoofed site again. In addition, clean devices connecting to the infected server will be compromised again.

How to Prevent?

When trying to prevent DNS spoofing, user-side protections are limited. Website owners and server providers have slightly more options to protect themselves and their users. To properly secure everyone, both sides must try to avoid fakes. To prevent attacks, website owners and DNS providers need to have:

1. Tools to detect DNS spoofing
2. End-to-end encryption
3. Domain name system security extensions

End users, on the other hand, must follow basic rules:

1. Never click on a link that you do not know
2. Scan your computer regularly for malware
3. Clean the DNS cache to solve the poisoning problem
4. Use a virtual private network (VPN)

Tips for DNS Server Providers and Website Owners

Protecting users lies entirely with the website owners or DNS server provider. Owners need to use various security tools and protocols to protect against threats. Among these resources are:

From the latest news in cybersecurity: Last weekend, hackers successfully attacked and corrupted the website of the Ministry of Construction, Housing and Communal Services of Russia.

Working Tips for Users

Users are especially vulnerable, so to avoid becoming a victim of a DNS poisoning attack, it’s essential to follow these simple tips:

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DNS (Domain name server) spoofing or DNS cache poisoning is a type of cyberattack used by an attacker to direct the victim’s traffic to a malicious website (instead of a legal IP address). Attackers use DNS cache poisoning to redirect Internet traffic and steal sensitive information.

For example, a hacker wants to trick users into entering personal information on an insecure site. How does he do that? By poisoning the DNS cache. The hacker spoofs or replaces the DNS data for a specific site and redirects the victim to the attacker’s server instead of the legitimate server. In this way, the hacker achieves his goal because he has many opportunities: he can commit a phishing attack, steal data or even inject malware into the victim’s system.

How Does DNS Spoofing Work?

Before talking about DNS cache poisoning, let’s first remember what DNS and DNS caching are. DNS is a worldwide directory of IP addresses and domain names. DNS pairs user-friendly addresses, such as facebook.com, into IP addresses, such as 157.240.22.35, that computers use on the network. DNS caching is a system for storing addresses on DNS servers worldwide. To speed up the processing of your DNS requests, developers have created a distributed DNS system. Each server keeps a list of available DNS records called a cache. If the DNS server closest to you does not have the required IP address, it queries the higher DNS servers until the address of the website you are trying to get to is not found. Your DNS server then saves this new record in your cache to get a response faster next time.

Unfortunately, DNS has several security flaws that attackers can exploit and insert forged Internet domain address records into the system. Typically, criminals send fake responses to the DNS server. The server then replies to the user who made the request, and at the same time, the legitimate servers will cache the fake record. Once the DNS cache server stores the fake pair, all subsequent requests for the compromised record will get the server’s address controlled by the attacker.

DNS Spoofing Techniques Can Include:

Cybercriminals can easily compromise DNS responses while remaining undetected due to security vulnerabilities in specific web applications and the lack of proper authentication of DNS records. Let’s take a closer look at them:

Lack of Verification and Validation

DNS has a first trust structure that does not require IP validation to verify before sending a response. Because DNS resolvers do not validate data in the cache, an invalid entry remains until it is manually deleted or the TTL expires.

Recursive DNS Resolver Vulnerability

When recursive querying is active, the DNS server receives the request and does all the work of finding the correct address and sending the response to the user. If it does not have a record in its cache, it will query other DNS servers until it gets the address and returns it to the user. Enabling recursive querying presents a security vulnerability that attackers can exploit to poison the DNS cache.

As the server looks for the address, the attacker can intercept the traffic and provide a fake response. The recursive DNS server will send the response to the user and simultaneously store the spoofed IP address in its cache.

No Encryption

Typically, the DNS protocol is not encrypted, making it easier for attackers to intercept its traffic. In addition, servers do not have to verify the IP addresses to which they route traffic. Hence they cannot determine whether it is genuine or spoofed.

How to Prevent DNS Spoofing?

Real-time monitoring of DNS data can help identify unusual patterns, user actions, or behaviors in traffic, such as visiting malicious sites. And while detecting DNS cache poisoning is difficult, there are several security measures companies and service providers can take to prevent it. Some measures to prevent DNS cache poisoning include using DNSSEC, disabling recursive queries, and more.

The Limit of The Trust Relationships

One of the vulnerabilities of DNS transactions is the high trust relationship between different DNS servers. Therefore, servers do not authenticate the records they receive, allowing attackers to send fake responses from their illegitimate servers.

To prevent attackers from exploiting this flaw, security groups should limit the level of trust their DNS servers have with others. Configuring DNS servers to not rely on trust relationships with other DNS servers makes it difficult for hackers to use a DNS server to compromise records on legitimate servers. There are many tools available to check for DNS security threats.

Use the DNSSEC protocol

Because Domain Name System Security Extensions (DNSSEC) uses public-key cryptography to sign DNS records, it adds validation and allows systems to determine whether an address is valid or not. This prevents forgery by verifying and authenticating requests and responses.

In regular operation, the DNSSEC protocol associates a unique cryptographic signature with other DNS information, such as CNAME and A records. The DNS resolver then uses this signature to authenticate the DNS response before sending it to the user.

Security signatures ensure that a legitimate source server validates responses to requests that users receive. Although DNSSEC can prevent DNS cache poisoning, it has drawbacks such as complex deployment, data provisioning, and zone enumeration vulnerabilities in earlier versions.

Use The Latest DNS and BIND Versions Software

Beginning with version 9.5.0 BIND (Berkeley Internet Name Domain) includes enhanced security features such as cryptographically secure transaction identifiers and port randomization, which minimizes the chance of DNS cache poisoning. It is also important that the IT staff keeps it up to date and ensures that it is the latest and safest version. Here are some more useful tips to help prevent DNS cache poisoning.

DNS cache poisoning causes domain users to be redirected to malicious addresses. In addition, some attacker-controlled servers can trick unsuspecting users into downloading malware or providing passwords, credit card information, and other confidential information. To prevent this, it is essential to use reliable security methods.

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