The ASEC analysis team is using the ASEC automatic analysis system RAPIT to categorize and respond to known malware. This post will list weekly statistics collected from June 20th, 2022 (Monday) to June 26th, 2022 (Sunday).
For the main category, info-stealer ranked top with 53.8%, followed by downloader with 25.1%, backdoor with 14.8%, banking malware with 4.9%, and ransomware with 1.3%.
Top 1 – AgentTesla
AgentTesla is an infostealer that ranked first place with 25.6%. It is an info-stealer that leaks user credentials saved in web browsers, emails, and FTP clients.
It uses e-mail to leak collected information, and there are samples that used FTP or Discord API. C&C information of recently collected samples is as follows.
- server : mail.contrivekota[.]in (184.168.102[.]151)
sender : hokota@contrivekota[.]in
receiver : info1@contrivekota[.]in
user : hokota@contrivekota[.]in
pw : Co****123$
- server : mail.focuzauto[.]com (166.62.10[.]145)
sender : whford@focuzauto[.]com
receiver : obtxxxtf@gmail[.]com
user : whford@focuzauto[.]com
pw : Gdn*016
- server : smtp.jubana[.]cam (208.91.199[.]223)
sender : slimshady@jubana[.]cam
receiver : slimshadyrrr@jubana[.]cam
user : slimshady@jubana[.]cam
pw : el***Mj_
As most are distributed through spam emails disguised as invoices, shipment documents, and purchase orders, the file names contain such words shown above (Invoice, Shipment, P.O. – Purchase Order). Multiple collected samples were disguised as files with extensions of pdf and xlsx.
- DOCUMENTS.exe RFQ_P.O#_AS894_-_SG633.exe
- swift copy.exe
- approved payment copy.exe
Top 2 – GuLoader
GuLoader, which ranked second place with 23.8%, is a downloader malware that downloads additional malware and runs it. It was packed with Visual Basic language in the past to avoid detection, but it is now distributed in a form of NSIS installer. It used to be known as CloudEye, but got a name GuLoader because Google Drive is frequently used as a download URL. In addition to Google Drive, various URLs such as One Drive from Microsoft can also be used.
Instead of being downloaded in a file form, GuLoader is downloaded on memory to avoid detection, and downloaded file is encoded, not PE. It then runs after decoding in the memory, downloading malware such as infostealer (Formbook, AgentTesla) and RAT (Remcos, NanoCore).
As most are distributed through spam emails disguised as invoices, shipment documents, and purchase orders, the file names contain such words shown above (Invoice, Shipment, P.O. – Purchase Order). Some samples have extensions disguised as document files such as pdf and xlsx or Auto CAD blueprint files such as dwg.
- Arrival Notice – Job no. SISGN2206003-01.exe
- Mateso 0620-220078.exe
- Purchase order_104121_90778_azBRIGHTOK.exe
- Remittance Advice.pdf.exe
Top 3 – Formbook
Formbook ranked third place with 20.2%.
Like other info-stealer, it is mainly distributed through spam emails. The distributed file names are close to each other.
- kosho_f.exe asian enterprise_template.exe
- PAYMENT COPY.exe
- PO-2022THERMAC06772 (Draft).exe
- estimates (forest job power plant) Arrival_notice.exe
As Formbook is injected into two normal processes (one is explorer.exe and the other in system32 directory), the malicious behaviors are performed by the normal processes. Besides user credentials in the web browser, the malware can steal various information through keylogging, clipboard grabbing, and web browser form grabbing.
Below is the list of confirmed C&C server URLs of Formbook.
Top 4 – Emotet
Emotet malware ranked fourth place with 4.9%. Emotet is a banking malware that is being continuously distributed via spam mails.
In its basic form, it is a downloader without additional features, but once installed on a system, it can download additional modules or additional malware.
Additional modules include user info-stealing modules that steal information such as web browser and e-mail credentials, and propagation module that spreads via shared folders. Additional malware strains include other banking malware such as Qakbot and Trickbot.
Top 5 – Remcos
This week, Remcos ranked fifth place with 4.5%. Remcos is a RAT malware that carries out various commands given by the attacker such as keylogging and information leaking.
Remcos is packed with a .NET packer and is distributed as attachments of spam emails, just like AgentTesla, Formbook, and NanoCore. Recently, there are some cases where it got distributed after disguising itself as a certain tool.
The confirmed C&C server URLs of Remcos are as follows.
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