Analyzing a malicious Raspberry Pi Bash script
Poison Dwarf
© Lead Image © Nelli Valova, 123RF.com
Analyze malware on hacked Raspberry Pis and create a signature to detect malware in log entries.
Raspberry Pis are being used more often by universities and scientific institutions, as well as for business computing. The small computers are often configured openly for easier usability, which means Rasp Pi users often execute every command with sudo without knowing the root password.
By default, the root has no password, but even if one were set, it does not have to be entered with sudo; therefore, the only difference between root and the pi user is that pi has to type sudo. In a learning environment for which the Raspberry Pi was designed, this is acceptable. In production use – especially when the computer can be accessed from the Internet – it is downright dangerous.
If you operate the Raspberry Pi without a monitor or keyboard (headless), you absolutely need SSH access. Although normally disabled, it is very easy to activate. If you do not change the default password of the pi user, then the computer is freely accessible over SSH. If it also turns out that the Raspberry Pi can be accessed through a firewall configuration that is too liberal or by way of port forwarding on the DSL router with an official IP address using port 22, you can expect someone to hack this computer. I had the opportunity to examine two such compromised Raspberry Pis.
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