Two Malware-Laced Gems Found in RubyGems Repository

Two Ruby gems that were found to pack malware capable of running persistently on infected machines were removed recently from the RubyGems hosting service.

The two gems, pretty_color and ruby-bitcoin, contained malware that was targeting Windows machines and which was meant to replace any cryptocurrency wallet address in the clipboard with an attacker-supplied one.

By replacing the crypto-wallet addresses, the malware helps the attackers hijack transactions and steal the victim’s funds.

While analyzing the two gems, software development and security firm Sonatype discovered that pretty_color contained legitimate files from colorize, a trusted open source component, which made detection more difficult.

“In fact, pretty_color is an identical replica of the benign colorize package and has all its code, including a fully descriptive README,” Sonatype says.

The gem included a file named version.rb that poses as version metadata, but which contains obfuscated code meant to run a malicious script on Windows computers.

The code also included a reference to ReversingLabs threat analyst Tomislav Maljic, who previously identified more than 700 typosquatting RubyGems designed to mine for Bitcoin on infected machines.

The ruby-bitcoin gem, Sonatype’s security researchers explain, only includes the malicious code present in the version.rb file from pretty_color.

A plain-text variant of the malicious script used in these gems was found on GitHub under an unrelated account, suggesting a possible connection to WannaCry. However, there’s no hard evidence linking the code to the WannaCry operation.

“Of all activities a ransomware group may conduct on a compromised system, replacing Bitcoin wallet address on the clipboard feels more akin to a trivial mischief by an amateur threat actor than to a sophisticated ransomware operation,” Sonatype notes.

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