At the turn of September and October 2014 the world learned of a security vulnerability that had been lurking for years in the GNU Bourne Again Shell (a.k.a. Bash). Most IT-security outlets had already covered the topic and published appropriate remediation methods, yet what caught my attention was the educational aspect of the flaw – in that regard it is a “good bug”, that is, one that can be used to explain many interesting mechanisms present in Unix-like systems.