July 2, 2022

A lately found RTF paperwork that comprise malicious VBA Macro code distributing to contaminate the home windows customers with harmful Distant entry Trojan ( RAT ). NetwiredRC and Quasar.

NetWiredRC and  Quasar is a distant entry Trojan that utilized by cyber-criminals to realize full management of sufferer’s laptop remotely.

Malware authors all the time discovering a novel solution to distributing and execute the malware utilizing varied social engineering methodology by way of malicious paperwork.

EHA

Each Distant entry Trojan able to performing varied malicious operations resembling distant webcam, distant shell and keylogging.

On this state of affairs, each essential RAT has dropped by macro comprise malicious RTF paperwork with Excel sheets.

Current days macro enabled malicious paperwork primarily based malware assaults are extensively found and stepping into massive quantity victims because the Microsoft paperwork are primarily used platform for the group in addition to people for varied operations.

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RAT An infection Stream with VBA Macro Code

Initially, the Malicious  RTF doc spreading by way of social engineering marketing campaign which consists of Macro Excel sheets.

As soon as a person clicks the  RTF Doc, embedded macro repeatedly exhibiting the popup and forcing customers to allow the Macros.

On this case, there isn’t any solution to cease the popups excepts to click on and pressure cease the entire paperwork and macro warning popup 1o instances as a result of it incorporates 10 excel paperwork.

An infection Stream

Malware writer used a way known as “objupdate” management in embedded excel sheet that helps to execute the Macro code through the RTF doc loaded and this methodology was abused the CVE-2017-0199, however it’s not used on this worst-case state of affairs.

In keeping with zscaler Reseachers, We noticed two variations of the malicious macro on this marketing campaign (see Fig. 5). Though the macro code is an identical, it’s executing the PowerShell command to obtain intermediate payloads utilizing Schtasks and cmd.exe.

Later Powershell downloads a malicious VBS Script and executes it the ultimate payload that NetwiredRC and QusarRat.

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The malware additionally completely allows macros for Phrase, PowerPoint, and Excel by doing registry modification and disable the protected view settings.