ezuri_unpack

ezuri_unpack

A simple unpacking script for the Ezuri ELF Crypter. Based on the analysis done by Ofer Caspi and Fernando Martinez of AT&T Alien Labs: https://cybersecurity.att.com/blogs/labs-research/malware-using-new-ezuri-memory-loader

How does it work?

The payload is encrypted with AES CFB and will be decrypted and run via memfd_create by the stub. Key and IV are stored in the binary.

Testing the script

1. Build the test payload gcc test.c -o test
2. Build and run guitmz/ezuri
3. To unpack it again: go run ezuri_unpack.go packed.bin

I also tested it with the packed Linux.Cephei sample mentioned in the report. Link to Virustotal