A Malicious Run-Only AppleScript (or Two) We believe that the method we used here is generalizable to other run-only AppleScripts and we hope this research will be helpful to others in the security community when dealing with malware using the run-only AppleScript format. However, with the help of a little-known applescript-disassembler project and a decompiler tool we developed here at SentinelLabs, we have been able to reverse these samples and can now reveal for the first time their internal logic along with further IoCs used in the campaign. Recent versions of macOS.OSAMiner add greater complexity by embedding one run-only AppleScript inside another, further complicating the already difficult process of analysis. In late 2020, we discovered that the malware authors, presumably building on their earlier success in evading full analysis, had continued to develop and evolve their techniques. Indeed, 360 MeshFire Team reported that the malicious applications:Ī similar conclusion was reached by another Chinese security researcher trying to dynamically analyse a different sample of macOS.OSAMiner in 2020, noting that “No reverse method has been found…so the investigation ends here” Investigations at the time concluded that macOS.OSAMiner, as we have dubbed it, had likely been circulating since 2015, distributed in popular cracked games and software such as League of Legends and MS Office.Īlthough some IoCs were retrieved from the wild and from dynamic execution by researchers, the fact that the malware authors used run-only AppleScripts prevented much further analysis. Symptoms included higher than usual CPU, system freeze and problems trying to open the system Activity Monitor.app. We have released our AEVT decompiler tool as open source to aid other researchers in the analysis of malicious run-only AppleScripts.īack in 2018, reports surfaced on Chinese security sites about a Monero mining trojan infecting macOS users.Combining a public AppleScript disassembler repo with our own AEVT decompiler tool allowed us to statically reverse run-only AppleScripts for the first time and reveal previously unknown details about the campaign and the malware’s architecture.macOS.OSAMiner has evolved to use a complex architecture, embedding one run-only AppleScript within another and retrieving further stages embedded in the source code of public-facing web pages.macOS.OSAMiner is a cryptominer campaign that has resisted full researcher analysis for at least five years due to its use of multiple run-only AppleScripts.
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