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 August 22nd, 2022 (Monday) to August 28th, 2022 (Sunday).
For the main category, info-stealer ranked top with 41.0%, followed by backdoor with 31.8%, downloader with 21.4%, and ransomware with 5.8%.
Top 1 – Agent Tesla
AgentTesla is an infostealer that ranked first place with 23.7%. 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.absheron-sharab[.]az (162.241.217[.]198)
- server: mail.spjsv[.]ro (89.43.174[.]45)
- server: mail.deanlogistics[.]org (192.185.147[.]82)
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, and P.O. – Purchase Order). Multiple collected samples were disguised as files with extensions of pdf and xlsx.
- Company profile and quotation p01234.exe
- BANK LETTER.pdf.exe
- Debit Advice.exe
- 2022 Q2 SIEMENS Energy -PO- 216238068.exe
- BALANCE PAYMENT.exe
- DHL Delivery Invoice.pdf.exe
- dhl intraship form.exe
- PURCHASE ORDER.exe
- Emirates NBD Bank Slip.exe
- Invoice Detailed_____pdf.exe
- Inquiry-ICMES-JIF-10-022 GI.exe
- payment advice.exe
Top 2 – RedLine
RedLine malware ranked second place with 12.1%. The malware steals various information such as web browsers, FTP clients, cryptocurrency wallets, and PC settings. It can also download additional malware by receiving commands from the C&C server. Like BeamWinHTTP, there have been numerous cases of RedLine being distributed under the disguise of a software crack file.
The following are the confirmed C&C server domains for RedLine:
Top 3 – Formbook
Formbook ranked third place with 11.6%.
Like other info-stealer, it is mainly distributed through spam emails. The distributed file names are close to each other.
- AHMR 4036.exe
- Quotation #24.08.2022.PDF.exe
- Shipping documents.exe
- SOA for July & August 2022.exe
- Purchase Order #08.22.2022.Pdf.exe
- DHL Shipment Delivery Notification 23-8-22.exe
- PO-8372929 .PDF.exe
- PRODUCT LIST.exe
- doc scanned copy.pdf.exe
- Product Inquiry.exe
- MV DOLPHIN 18_SHIP-PARTICULARS.exe
Formbook is injected into normal processes (one is a running explorer.exe and the other in system32) that perform malicious behaviors. 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 – GuLoader
GuLoader, which ranked fourth place with 11.0%, is a downloader malware that downloads additional malware and runs it. It was packed with Visual Basic language in the past to bypass detection, but it is now distributed in a form of an NSIS installer. It used to be known as CloudEye but got the 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 and Discord can also be used.
Instead of being downloaded in a file form, GuLoader is downloaded on memory to avoid detection, and the downloaded file is encoded, not PE. It is then executed after being decoded in the memory, downloading malware such as infostealer (Formbook and AgentTesla) and RAT (Remcos and 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, and 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.
- DETAILS AND INVOICES.exe
- JUSTIFICANTE DE PAGO.exe
- Factura 00347.exe
- Punktummer Femtedelene.exe
- REQUEST FOR QUOTE (SUPPLIES).exe
- NEW ORDER.exe
- DETALLES Y FACTU/DETALLES Y FACTURAS.exe
- Statement of Accounts.exe
- DETAILS AND INVO/DETAILS AND INVOICES.exe
- Punktummer Femtedelene.exe
Top 5 – Remcos
This week, Remcos ranked fifth place with 8.7%. 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 to 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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