What is DNS cache poisoning attack? Core principle and harm analysis

behind the network access, the DNS system is like the navigator of the Internet, responsible for converting domain names into identifiable Internet Protocol Addresses to ensure the normal operation of various network services. But this core system also faces a variety of security threats, DNS cache poisoning attack is one of the most destructive one. This article will dismantle the whole picture of DNS cache poisoning attack for readers from multiple dimensions of principle, harm, identification and protection, help you recognize the essence of such attacks, and improve cyber security awareness.

, what is the core principle of DNS cache poisoning attack?

to understand the DNS cache poisoning attack, we must first start with the cache mechanism of the DNS system, which is the basic condition for the attack to be implemented.

1, the role of DNS cache and vulnerability basis

DNS cache is a storage area set by the DNS server to improve the resolution efficiency and reduce repeated queries. When a user queries the Internet Protocol Address of a domain name, the server will cache the corresponding result for a period of time. The DNS cache poisoning attack takes advantage of the verification vulnerability in the DNS query process. The attacker does not need to directly control the target DNS server, but only needs to construct a fake DNS response packet to make the server associate the wrong Internet Protocol Address with the domain name and cache it, so as to achieve the purpose of tampering with the resolution result.

2, DNS cache poisoning attack implementation logic

attack lies in forging legitimate DNS response packets. The attacker will first send a large number of fake domain name query requests to the target DNS server to obtain the random ID of the query, and then quickly construct a response packet containing the wrong Internet Protocol Address, which will be delivered before the server receives the real response. Once the server verifies the fake response packet, it will store the wrong resolution result in the cache. When subsequent users query the domain name, they will be directed to the malicious address preset by the attacker.

What are the typical hazards of DNS cache poisoning attacks?

DNS cache poisoning attack is not limited to a single user, but also affects all client bases using the poisoned DNS server, which has a wide range of damage and deep impact.

1, user information leakage and property damage

when the user is directed to the fake phishing site, often mistaken for a regular platform, and then enter the account password, bank card information and other sensitive content, this information will be directly obtained by the attacker, eventually resulting in the user's property is stolen brush or personal information is resold. This kind of DNS cache poisoning attacks caused by phishing events, has caused large-scale user information leakage, bringing serious economic losses.

2, network service availability affected

attackers can also use DNS cache poisoning attacks to direct users' requests to Internet Protocol Addresses that cannot be accessed normally, causing users to be unable to open regular websites and directly affecting the service availability of websites. For enterprises, this will cause customer loss, brand perception damage, and some enterprises that rely on network services will even experience business stagnation, resulting in huge operational losses.

3, malicious software propagation channel

attackers may also direct users to sites containing malicious software, during the user's visit, the device will download and install viruses, Trojans and other malicious programs without perception, these programs will steal private data in the device, and even control The device becomes part of a botnet, further expanding the scope of DNS cache poisoning attacks.

How to identify DNS cache poisoning attack?

timely identify DNS cache poisoning attacks, can effectively reduce the losses caused by the attack, to avoid more users are affected.

1, abnormal analysis results troubleshooting

users can query the Internet Protocol Address of the same domain name through different devices or networks. If the results are inconsistent, they may encounter a DNS cache poisoning attack. In addition, if the original normal website is suddenly inaccessible, or jumps to an unfamiliar page, you need to be vigilant about whether there is a DNS cache poisoning attack. At this time, you can confirm the authenticity of the resolution results through professional DNS query tools.

2, server cache log analysis

For DNS server administrators, regularly checking the cache logs is the key to identifying attacks. If a large number of unfamiliar domain name resolution requests appear in the logs, or the same domain name appears multiple different resolution results in a short period of time, it may be that the attacker is implementing DNS cache poisoning attacks, and the server cache needs to be checked and cleaned immediately.

How to prevent DNS cache poisoning attacks?

the characteristics of DNS cache poisoning attacks, users and enterprises can start from multiple levels to build a sound protection system.

1, use a secure and reliable DNS server

ordinary users should prefer public DNS servers that have been certified for security. Such servers usually have perfect protection mechanisms to effectively resist DNS cache poisoning attacks. Enterprise users can set up their own internal DNS servers and regularly update the server software to fix known security bugs to reduce the risk of being attacked from the source.

2 Enable DNSSEC Security Extensions

DNSSEC is a security protocol specially designed for DNS system. It verifies the legitimacy of DNS response packets through digital signatures and ensures the authenticity and integrity of resolution results. After enabling DNSSEC, the DNS server will sign and verify the received response packets. Only the verified response packets will be stored in the cache, which can fundamentally prevent the false response packets of DNS cache poisoning attacks from taking effect.

3, strengthen network monitoring and cache management

enterprises should establish a real-time network monitoring system, real-time analysis of DNS query and response data, and timely detection of abnormal traffic. At the same time, reasonably set the expiration time of DNS cache, shorten the retention time of wrong resolution results, even if DNS cache poisoning attack, can quickly restore normal resolution services.

To sum up, DNS cache poisoning attack is a malicious network attack against DNS system cache mechanism, the core of which is to forge false response packets and tamper with the resolution results, which will cause user information leakage, service interruption and other hazards. By identifying abnormal resolution results and analyzing server logs, such attacks can be found in time, and choosing a secure DNS server, enabling DNSSEC and strengthening monitoring are effective means of protection. Only by fully understanding and taking precautions can we ensure the security and reliability of network access.