Backdoor code was found added in a popular Ruby library used for frontend user interfaces inside Ruby and Ruby on Rails applications. The malicious code was removed via a library update.

B. Efron, R. Tibshirani, Bootstrap Methods for Standard Errors, Confidence Intervals, and Other Measures of Statistical Accuracy, Statistical Science, Vol. 1, No. 1 ...

Polymorphic bootstrap code Since Rovnix.B the modified bootstrap code has used polymorphic code in order to bypass static antivirus signature detection.