Ops One AG platform status and maintenance announcements. Times are indicated in local Swiss time. https://opsone.ch/.

Monday 13th December 2021

Managed Server Version 7: Web Application Firewall: Additional Rules to mitigate CVE-2021-44228 (Log4j)

Our web application firewall does already detect all known exploits targeting arbitrary GET and POST parameters (CRS rule 932130). However, the rule did not inspect HTTP headers such as the user-agent and referrer yet.

To mitigate attacks against this vulnerability, we

  • added the User-Agent and Referer headers to the targets of the CRS rule 932130
  • added another, targeted rule against the usage of jndi strings

Even though the web application firewall does protect your applications from this issue unless manually disabled, make sure to take the required steps to mitigate the problem at its source, as outlined by Log4j here.

Reference #1093