[oss-security] CVE request: PowerDNS in default configuration is vulnerable to DoS attack

2014-06-14T00:00:00
ID SECURITYVULNS:DOC:30877
Type securityvulns
Reporter Securityvulns
Modified 2014-06-14T00:00:00

Description

It was found 1 that in default configuration PowerDNS is allowed to consume more file descriptors than is available for a default installation of many Linux distributions. Default configuration is: 2 threads / 2048 max-mthreads, which leads to a theoretical FD consumption of 4096. Default FD limit on many distributions is 1024. This can potentially lead to the DoS attack.

Workaround (from 1):

  • Reduce max-mthreads to 512 (or threads to 1 and max-mthreads to 1024) (max-mthreads was introduced in Recursor 3.2; but if you are running a version that old, please upgrade it!)
  • Run ‘ulimit -n 32768? before starting (perhaps put this in /etc/init.d/ script). There’s little reason to skip on this number.
  • Investigate defaults in /etc/security/limits.conf

Patch is available at 2

References:

https://bugs.mageia.org/show_bug.cgi?id=13521 https://bugzilla.redhat.com/show_bug.cgi?id=1109231

Can a CVE please be assigned if one has not been already?

Thanks. -- Vasyl Kaigorodov | Red Hat Product Security Team PGP: 0xABB6E828 A7E0 87FF 5AB5 48EB 47D0 2868 217B F9FC ABB6 E828