[clamav-users] [ext] Re: Vbs.Trojan.AsyncRAT-9889434-1

[Andrew Salway]

Thanks again, that’s very helpful 😊


From: clamav-users <clamav-users-bounces at lists.clamav.net> on behalf of Ralf Hildebrandt via clamav-users <clamav-users at lists.clamav.net>
Date: Wednesday, 17 May 2023 at 10:02
To: clamav-users at lists.clamav.net <clamav-users at lists.clamav.net>
Cc: Ralf Hildebrandt <Ralf.Hildebrandt at charite.de>
Subject: Re: [clamav-users] [ext] Re: Vbs.Trojan.AsyncRAT-9889434-1
CAUTION: This email originated from outside of CYSIAM. Do not click on any links or attachments unless you trust the sender and know the content to be safe.

* Andrew Salway via clamav-users <clamav-users at lists.clamav.net>:
> Many thanks Ralf for the speedy reply.
>
> Is it then triggered if the three strings (urldecode, msbuild.exe, .xml) are all present anywhere in a normalised ASCII file?

Probably. As long as the file is smaller then 2097152 bytes.

> # sigtool --find="Vbs.Trojan.AsyncRAT-9889434-1" | sigtool --decode
>
> VIRUS NAME: Vbs.Trojan.AsyncRAT-9889434-1
> TDB: Engine:90-255,FileSize:0-2097152,Target:7
>
> LOGICAL EXPRESSION: 0&1&2
> * SUBSIG ID 0
> +-> OFFSET: ANY
> +-> SIGMOD: NONE
> +-> DECODED SUBSIGNATURE:
> urldecode
>
> * SUBSIG ID 1
> +-> OFFSET: ANY
> +-> SIGMOD: NONE
> +-> DECODED SUBSIGNATURE:
> msbuild.exe
>
> * SUBSIG ID 2
> +-> OFFSET: ANY
> +-> SIGMOD: NONE
> +-> DECODED SUBSIGNATURE:
> .xml
>
> So it must be 0 AND 1 and 2.
>
> 0 is urldecode ANYWHERE
> 1 is msbuild.exe ANYWHERE
> 2 is .xml ANYWHERE

--
Ralf Hildebrandt
Charité - Universitätsmedizin Berlin
Geschäftsbereich IT | Abteilung Netzwerk

Campus Benjamin Franklin (CBF)
Haus I | 1. OG | Raum 105
Hindenburgdamm 30 | D-12203 Berlin

Tel. +49 30 450 570 155
ralf.hildebrandt at charite.de
https://www.charite.de<https://www.charite.de>
_______________________________________________

Manage your clamav-users mailing list subscription / unsubscribe:
https://lists.clamav.net/mailman/listinfo/clamav-users<https://lists.clamav.net/mailman/listinfo/clamav-users>


Help us build a comprehensive ClamAV guide:
https://github.com/Cisco-Talos/clamav-documentation<https://github.com/Cisco-Talos/clamav-documentation>

https://docs.clamav.net/#mailing-lists-and-chat<https://docs.clamav.net/#mailing-lists-and-chat>

Disclaimer

The information contained in this communication from the sender is confidential. It is intended solely for use by the recipient and others authorized to receive it. If you are not the recipient, you are hereby notified that any disclosure, copying, distribution or taking action in relation of the contents of this information is strictly prohibited and may be unlawful.

This email has been scanned for viruses and malware, and may have been automatically archived by Mimecast, a leader in email security and cyber resilience. Mimecast integrates email defenses with brand protection, security awareness training, web security, compliance and other essential capabilities. Mimecast helps protect large and small organizations from malicious activity, human error and technology failure; and to lead the movement toward building a more resilient world. To find out more, visit our website.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.clamav.net/pipermail/clamav-users/attachments/20230517/64305c35/attachment.htm>