DNS exploit in the wild

We’ve been tracking Metasploit commits since Matasano’s premature publication of [Dan Kaminsky]’s DNS cache poisoning flaw on Monday knowing full well that a functional exploit would be coming soon. Only two hours ago [HD Moore] and [I)ruid] added a module to the Metasploit Project that will let anyone test the vulnerability (with comment: “ZOMG. What is this? >:-)“). [HD] told Threat Level that it doesn’t work yet for domains that are already cached by the DNS server, but it will automatically wait for the cached entry to expire and then complete the attack. You can read more about the bailiwicked_host.rb module in CAU’s advisory. For a more detailed description of how the attack works, see this mirror of Matason’s post. You can check if the DNS server you are using is vulnerable by using the tool on [Dan]’s site.

[photo: mattdork]

Major DNS issue causes multivendor patch day

Earlier this year, our friend [Dan Kaminsky] discovered a major DNS issue that could allow hackers to compromise name servers and clients easily. The vulnerability involves cache poisoning, and [Kaminsky] plans to publish the full details of the vulnerability on August 6th. However, he has already begun his work to control it, alerting major authorities early on of the vulnerability.

As a result, engineers from many major technology vendors quickly began working on coordinated patches for DNS servers. The patches were all released today; vendors and a CERT advisory urge organizations to apply them today, before the vulnerability becomes common knowledge. More details on the DNS issue can be found in the executive overview (PDF file). [Rich Mogull] interviewed [Dan] for the Network Security Podcast. It doesn’t detail the attack but points out that services that use port randomization like OpenDNS are unaffected and that Bind8 is being deprecated.

UPDATE: Here’s the audio from this morning’s press conference.

[image: Flickr / d70focus ]

Malware alters DNS data on routers

The Zlob trojan, also known as DNSChanger, has been around for a few years, but recent Zlob variants to appear in the wild attempt to log into routers using a list of default admin/password combos. If they succeed, they alter the DNS records on the router to reroute traffic through the attacker’s server.

Our friend [Dan Kaminisky] recently did a presentation warning against vulnerabilities in internet browser plugins that allow attackers to mount DNS rebinding attacks against routers with default passwords.. Though it achieves the same end, Zlob is different because it infects by the tried-and-true method of fooling users into downloading it inside a fake video codec. Once it is running on a client machine, it is free to attempt to use the default admin id and password of the router to log in and alter DNS settings. It even supports the DD-WRT firmware.

Even if a system is wiped clean of Zlob trojans, the router could still be compromised. The good news is that it is easy to fix and even easier to prevent. Fixing it takes no more than wiping all network clients clean, then resetting the router and restoring custom settings. Prevention is a simple matter of changing the router’s password.

[photo: fbz]