Undetected sample: 'awvjtnz'

[robbat2]

Sample is attached here:
https://gist.github.com/robbat2/f3e62e360f7eb1dab1a02c1e535039b8

Suggested detection:
Look for large strings that contain a string-reversed create_function, but be sure to check case-insensitive.

[jvoisin]

Thanks, done in a33ecf9.