Cache poisoning is a method for compromising DNS data by inserting malicious or misleading information into DNS caches. The Domain Name System (DNS) translates human-friendly domain names into the numerical IP addresses used by computers to communicate on the Internet. In order to maximize efficiency, DNS is distributed over many servers and cached at multiple levels, from local DNS resolvers to authoritative DNS servers.
To save time and resources from continually looking up the same domain, caching DNS servers temporarily store DNS records. The local DNS resolver contacts the authoritative DNS servers to get the correct IP address whenever a user makes a request to a website. Next, the "time to live" (TTL) of the cached answer is determined. Cache poisoning attacks are launched to replace this cached data with malicious information and trick users into visiting compromised websites.
Cache poisoning often involves a local DNS resolver and an authoritative DNS server, both of which might be vulnerable to attacks. There are essentially four stages to this procedure:
- Request for Resolution: The DNS resolution process begins when a user's device, such as a computer or smartphone, requests the IP address of a specific domain name.
- Local DNS Resolver: In order to determine the IP address associated with the requested domain name, the request is transmitted to a local DNS resolver. Frequent site records may already be cached by the local DNS resolver, allowing it to accelerate the process.
- Query to Authoritative DNS Server: When the IP address of the requested domain is either absent from the local cache or has expired (as indicated by the TTL), the local DNS resolver initiates a query to an authoritative DNS server. The authoritative records for a given domain are stored on these authoritative servers.
- Authoritative Response: The authoritative DNS server furnishes the local DNS resolver with the accurate IP address, which is subsequently cached for future utilization.
- Cache Poisoning Attack: A cache poisoning assault occurs when an adversary manipulates or spoofs a reply originating from the authoritative DNS server. This reply comprises erroneous or malevolent information, including an alternative IP address. Following this, the malicious data is cached by the local DNS resolver.
- User Redirection: Upon attempting to access the compromised domain, the user is forwarded to the IP address that the malicious data has supplied. This website may be fraudulent, with the intention of distributing malware or stealing sensitive data.
Cache poisoning can manifest in diverse forms, employing a multitude of techniques to undermine DNS data. Examples of prevalent methodologies encompass:
- DNS Spoofing: DNS deception occurs when an assailant intercepts queries sent to the DNS and generates deceptive responses, typically preceding the response time of the authentic DNS server. Local DNS resolvers subsequently cache this fraudulent information.
- Pharming: Pharming is a variant of cache poisoning that is more persistent. Compromising the DNS configuration of a user's router or computer enables the redirection of the user to a malevolent website, irrespective of the user entering the authentic URL.
- IDN Homograph Attack: In this assault, malevolent entities employ internationalized domain names (IDNs) to generate domain names that exhibit an aesthetic resemblance to authentic domains. Users may be duped and directed to malicious websites as a result.
- DNS Cache Poisoning with Malware: Malware can modify DNS data on a victim's computer or network, diverting users to malicious websites. The malware, for example, may modify the DNS server settings to those controlled by the attacker.
- Domain Hijacking: Attackers may get illegal access to a domain owner's account or registrar, enabling them to modify the DNS records for a genuine domain.
Protecting against cache poisoning, a sort of hack that manipulates the Domain Name System (DNS), is critical for ensuring the security and integrity of your network and online activity.
Mitigation Strategies:
Implement DNSSEC (DNS Security Extensions):
One essential piece of technology to stop cache poisoning is DNSSEC. By digitally signing DNS records, it enhances DNS security. A DNS resolver can confirm the digital signature to confirm the legitimacy of the contents when it receives a DNSSEC-protected response. Cache poisoning attacks are significantly more difficult to carry out thanks to DNSSEC's assistance in preventing the introduction of malicious data into DNS caches.
Use Trusted DNS Servers:
Make that the DNS servers on your network and devices are reliable and trustworthy. DNS servers are offered by the majority of Internet service providers (ISPs), but you may also want to use well-known public DNS services like Cloudflare DNS or Google Public DNS. Cache poisoning attacks are less likely to affect trusted DNS servers.
Keep DNS Software Up to Date:
Update the security patches and software on your DNS server on a regular basis. Attackers may leverage DNS server software vulnerabilities to enable cache poisoning. Updates to the software help reduce these hazards.
Implement Rate Limiting:
Set up your DNS resolver to use rate limitation. The amount of DNS inquiries that can be accepted from a single source within a given time frame is limited by rate limitation. As a result, attackers are unable to flood the DNS server with fraudulent requests, limiting the effectiveness of cache poisoning attempts.
Network Segmentation:
Isolate DNS servers from potentially dangerous networks. By segmenting your network, you lower the attack surface and the possibility of cache poisoning assaults originating elsewhere on your network.
Monitor DNS Traffic and Behavior:
Implement strong DNS traffic monitoring and logging. Examine logs on a regular basis for unusual or suspicious activities. An unusual pattern could signal a cache poisoning attempt. Prompt detection can assist you in taking action before the attack is successful.
Use DNS Filtering Services:
Use DNS filtering services to help prevent access to known malicious domains. These services maintain dangerous website databases and can restrict visitors from accessing them, lowering the risk of cache poisoning.
Multi-Factor Authentication (MFA):
Multi-factor authentication protects your domain registrar accounts. Attackers acquiring unauthorized access to your domain registrar and changing DNS records can facilitate cache poisoning. MFA increases security by requiring a second form of authentication in addition to a password.
Secure Network Devices:
Protect against pharming attacks by ensuring that all network devices, including routers, are properly setup. In order to divert traffic, phishing attempts frequently alter DNS settings on routers. If you want to keep your network secure, you should regularly check and update the firmware on your devices.
User Education:
You should warn your visitors about the dangers of cache poisoning and advise them to check the security of any website before inputting personal data or making financial transactions. Make sure they know to only visit websites that have a secure connection (https://) and a current SSL/TLS certificate.
Regular Security Audits:
Audit and test your network's vulnerability to intrusion on a regular basis. Cache poisoning attacks can be avoided if flaws and vulnerabilities are discovered beforehand.
Backup DNS Servers:
Keep a ready supply of secondary DNS servers to roll out in the event of a cache poisoning attack. While the assault is being mitigated, DNS services can be restored with the use of backup servers with clean, uncontaminated DNS data.
As a result, preventing cache poisoning is crucial to ensuring the safety of your network and online activity in general. Cache poisoning can be avoided by taking basic precautions such implementing DNSSEC, utilizing trusted DNS servers, updating software, and following best practices for network and device security. The threat of cache poisoning attacks can be greatly mitigated by implementing these safeguards in tandem with constant monitoring and thorough user education.