The exploit targets a vulnerability in Bind 9, the most widely used DNS server standard, warned the Internet Systems Consortium (ISC) on Tuesday. ISC is the organisation that supports Bind.
The hole in Bind 9 has no workaround. Administrators must upgrade to Bind versions 9.4.3-P3, 9.5.1-P3 or 9.6.1-P1 to mitigate the threat. The exploit, which a hacker could use to launch an attack against unpatched master servers, is easily available, warned ISC.
"An active remote exploit is in wide circulation at this time," said ISC in an advisory.
The Berkeley Internet Name Domain (Bind) is the most widely used DNS server standard. Bind 9 was coded to overcome security issues associated with Bind, and supports DNS Security Extensions, (DNSSEC), or encrypted DNS.
The Bind 9 dynamic update DOS vulnerability affects master servers for one or more zones. Receipt of a specially crafted dynamic update message may cause Bind 9 master servers to crash, said ISC.