DNS cache poisoning attack protection guide: master the key defense steps

in the current complex network environment, DNS is the core hub of domain name and Internet Protocol Address conversion. Once there is a security problem, it will directly threaten the access security of the entire network. DNS cache poisoning attack is a typical malicious means for DNS system. Attackers tamper with the domain name resolution records in the DNS server cache to guide users to phishing websites or malicious servers, and then steal information and implant malicious programs. This article will sort out a complete set of DNS cache poisoning attack defense plans for you from attack identification, basic protection, advanced reinforcement to emergency response, and help you build a cyber security defense line.

, how to identify DNS cache poisoning attack?

to prevent DNS cache poisoning attacks, we must first be able to accurately identify the characteristics of such attacks, to avoid the attack is still undetected.

1, exception resolution jump

when the user visits the familiar formal domain name, but jump to unfamiliar websites, or page content and the official website there are obvious differences, this is the most intuitive performance of DNS cache poisoning attack. For example, visit the bank's official website but enter the phishing page, then the probability is that the DNS cache in the resolution record has been tampered with.

2, parsing record abnormal change

regularly check the cache records of the DNS server. If it is found that the resolution records without reasonable basis are added, modified or deleted, especially the records pointing to the unknown Internet Protocol Address, it is necessary to be vigilant against the occurrence of DNS cache poisoning attacks. In addition, there are multiple different resolution results for the same domain name, and some of the results are unknown, which is also an abnormal situation.

Second, the basic protection steps of DNS cache poisoning attack

basic protection is the first barrier against DNS cache poisoning attacks, which can reduce the probability of successful attacks from the source.

1 Choose a trusted DNS server

give preference to trusted DNS servers from official operators and well-known public service providers. Such servers usually have perfect security protection mechanisms, which can effectively reduce the risk of DNS cache poisoning attacks. Avoid using third-party DNS servers of unknown origin to prevent yourself from being the target of attacks.

2 Enable DNSSEC verification mechanism

DNSSEC is a domain name system security extension, which verifies the authenticity and integrity of DNS resolution records through digital signatures, which can effectively prevent attackers from tampering with cache records. Enabling DNSSEC function in DNS server and client side can ensure that the resolution records obtained by users are from regular domain name servers, fundamentally preventing DNS cache poisoning attacks.

3. Advanced reinforcement measures for DNS cache poisoning attacks

on the basis of basic protection, through advanced reinforcement measures, the DNS system can further enhance the ability to resist DNS cache poisoning attacks.

1 Limit DNS cache duration

reasonably set the expiration time of DNS cache and shorten the retention time of cache records. Even if a DNS cache poisoning attack occurs, the tampered records will fail faster and reduce the impact range caused by the attack. Generally, the cache duration can be set to 1 hour to 4 hours, which can be flexibly adjusted according to the update frequency of the domain name.

2, configure DNS access control policy

configure strict access control policies for DNS servers, allowing only trusted client side and upstream DNS servers to communicate, and rejecting requests from unknown Internet Protocol Addresses. At the same time, limit the number of query requests initiated by DNS servers to prevent attackers from implementing DNS cache poisoning attacks through a large number of forged requests.

3 Enable the EDNS0 extension

EDNS0 extensions can expand the capacity of DNS data packets and support more security options, such as adding randomized query IDs and source ports, making it more difficult for attackers to guess these parameters, thus reducing the success rate of DNS cache poisoning attacks. In modern DNS servers, EDNS0 is usually supported by default, just make sure it is enabled.

4. Emergency response plan for DNS cache poisoning attack

even if the full protection, may also encounter DNS cache poisoning attack, at this time a set of perfect emergency response scheme can quickly control the loss, restore the normal operation of the network.

1, immediately clean the exception cache record

once you find signs of DNS cache poisoning attack, log in to the DNS server as soon as possible, clean up all abnormal resolution records, and force refresh the cache to ensure that subsequent resolution requests can obtain the correct records. After cleaning, you need to continue to monitor the cache status to prevent attackers from tampering again.

2, identify the source of the attack and block

check the source Internet Protocol Address of the attack request through the log records of the DNS server, add rules in the firewall and intrusion detection system to block all communication of the Internet Protocol Address. At the same time, check whether there are invaded devices in the network to prevent attackers from using internal devices to launch continuous DNS cache poisoning attacks.

To sum up, DNS cache poisoning attacks are an important risk that threatens the security of network access. To do a good job in protection, it is necessary to make a comprehensive layout from identification, basic protection, advanced reinforcement to emergency response. By accurately identifying attack characteristics, building basic protection barriers, implementing advanced reinforcement measures, and cooperating with a perfect emergency response plan, the probability of DNS cache poisoning attacks can be effectively reduced, and losses can be quickly stopped in the event of an attack to ensure the security and stability of network access.