IronNetInjector: Turla’s New Malware Loading Tool

In recent years, more and more ready-made malware is released on software development hosting sites available for everybody to use – including threat actors. This not only saves the bad guys development time, but also makes it much easier for them to find new ideas to prevent detection of their malware.

Unit 42 researchers have found several malicious IronPython scripts whose purpose is to load and run Turla’s malware tools on a victim’s system. The use of IronPython for malicious purposes isn’t new, but the way Turla uses it is new. The overall method is known as Bring Your Own Interpreter (BYOI). It describes the use of an interpreter, not present on a system by default, to run malicious code of an interpreted programming or scripting language.

The first malicious IronPython scripts of the tool we describe here were discovered last year by a security researcher from FireEye. At the beginning of this year, another security researcher from Dragos pointed out some new scripts of the same threat actor uploaded to VirusTotal from two different submitters. We found that one of the submitters also uploaded two other samples, which are most likely embedded payloads of one of the IronPython scripts. These samples helped us to understand how this tool works, what malware it loads and which threat actor uses it.

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Source: Palo Alto