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 September 5th, 2022 (Monday) to September 11th, 2022 (Sunday).
For the main category, info-stealer ranked top with 47.1%, followed by downloader with 32.7%, backdoor with 12.5%, and ransomware with 7.7%.
Top 1 – GuLoader
GuLoader, which ranked first place with 21.1%, 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.
- Fiberplade Smartening.exe
- Havbiologerne Fjervgtene.exe
- Mongoloidt Genitialfases.exe
Top 2 – AgentTesla
AgentTesla is an infostealer that ranked second place with 20.2%. 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.rimiapparelsltd.com
- server: mail.rimiapparelsltd.com
- server: mail.stamnas.gr
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.
- Inquiry No. EI2022-5002.exe
- TNT SHIPPING DOC.exe
- PO- 220128.exe
Top 3 – Lokibot
Lokibot malware ranked third place with 12.5%. It is an info-stealer that leaks information about programs such as web browsers, email clients, and FTP clients.
The following is a list of the most C&C servers for the malware.
Top 4 – SmokeLoader
Smoke Loader is an info-stealer or downloader malware that ranked fourth place with 10.6%. For an analysis report related to Smoke Loader, refer to the ASEC Report below.
The confirmed C&C server URLs are as follows.
Top 5 – Formbook
Formbook ranked fifth place with 9.6%.
Like other info-stealer, it is mainly distributed through spam emails. The distributed file names are close to each other.
- IMABARI 38K DWT SDBC LOGGER.exe
Formbook is injected into normal processes (one is a running explorer.exe and the other is 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.
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