Iratxe001

**Name of the Vulnerable Software and Affected Versions** Graylog versions prior to 5.0.9 Graylog versions prior to 5.1.3 **Description** Graylog makes use of only one single source port for DNS queries, which goes against recommended practice since 2008, when Dan Kaminsky discovered how easy it is to carry out DNS cache poisoning attacks. To prevent cache poisoning with spoofed DNS responses, it is necessary to maximize the uncertainty in the choice of a source port for a DNS query. Although unlikely in many setups, an external attacker could inject forged DNS responses into Graylog's lookup table cache. In order to prevent this, it is at least recommendable to distribute the DNS queries through a pool of distinct sockets, each of them with a random source port and renew them periodically. **Recommendations** For Graylog versions prior to 5.0.9, upgrade to version 5.0.9 or later. For Graylog versions prior to 5.1.3, upgrade to version 5.1.3 or later. As a temporary workaround, consider distributing the DNS queries through a pool of distinct sockets, each of them with a random source port and renew them periodically, until a patch is available.