CAPEC-142 DNS Cache Poisoning

A domain name server translates a domain name (such as www.example.com) into an IP address that Internet hosts use to contact Internet resources. An adversary modifies a public DNS cache to cause certain names to resolve to incorrect addresses that the adversary specifies. The result is that client applications that rely upon the targeted cache for domain name resolution will be directed not to the actual address of the specified domain name but to some other address. Adversaries can use this to herd clients to sites that install malware on the victim's computer or to masquerade as part of a Pharming attack.

1. [Explore] [Explore resolver caches] Check DNS caches on local DNS server and client's browser with DNS cache enabled. 2. [Experiment] [Attempt sending crafted records to DNS cache] A request is sent to the authoritative server for target website and wait for the iterative name resolver. An adversary sends bogus request to the DNS local server, and then floods responses that trick a DNS cache to remember malicious responses, which are wrong answers of DNS query. 3. [Exploit] [Redirect users to malicious website] As the adversary succeeds in exploiting the vulnerability, the victim connects to a malicious site using a good web site's domain name.

• A DNS cache must be vulnerable to some attack that allows the adversary to replace addresses in its lookup table.Client applications must trust the corrupted cashed values and utilize them for their domain name resolutions.

• [Medium] To overwrite/modify targeted DNS cache

• Configuration: Make sure your DNS servers have been updated to the latest versions • Configuration: UNIX services like rlogin, rsh/rcp, xhost, and nfs are all susceptible to wrong information being held in a cache. Care should be taken with these services so they do not rely upon DNS caches that have been exposed to the Internet. • Configuration: Disable client side DNS caching.