Gird your loins internet: Attackers now have the ability to disrupt large swathes of the web through a remote denial of service vulnerability found in the most widely used software for DNS servers.
The BIND bug (CVE-2015-5477) patched overnight affects all DNS servers running the software, and can be attacked with ease.
In fact a researcher has already developed an attack capable of knocking servers offline with a single packet.
Internet Systems Consortium Michael McNally, lead investigator for the bug, says there are no workarounds other than to apply a patch. He expects attacks to happen soon.
“The practical effect of this is that this bug is difficult to defend against (except by patching, which is completely effective) and will not be particularly difficult to reverse-engineer,” McNally says.
“I have already been told by one expert that they have successfully reverse-engineered an attack kit from what has been divulged and from analysing the code changes, and while I have complete confidence that the individual who told me this is not intending to use his kit in a malicious manner, there are others who will do so who may not be far behind.”
Attackers can send a crafted DNS query packet to trigger a REQUIRE assertion failure, causing BIND to exit.
The bug is labeled a critical fix and “deserves that designation,” McNally says.
It stands out among other BIND bugs in that it affects almost all known BIND servers and cannot be mitigated without a patch. Firewalls will likely not help.
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