AhnLab Security Emergency response Center (ASEC) uses the ASEC automatic analysis system RAPIT to categorize and respond to known malware. This post will list weekly statistics collected from May 1st, 2023 (Monday) to May 7th, 2023 (Sunday).
For the main category, infostealer ranked top with 60.6%, followed by downloader with 27.3%, backdoor with 9.1%, and ransomware with 3.0%.
Top 1 – AgentTesla
AgentTesla is an infostealer that ranked first place with 25.8%. It leaks user credentials saved in web browsers, emails, and FTP clients.
Top 2 – Formbook
Formbook ranked second place with 20.5%.
Like other Infostealers, it is mainly distributed through spam emails. The distributed file names are close to each other.
- New purchase order teams.pdf.exe
As Formbook is injected into normal processes (one is a running explorer.exe and the other is in system32), the malicious behaviors are performed by these 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 3 – Amadey
This week, Amadey Bot ranked third place with 17.4%. Amadey is a downloader that can receive commands from the attacker to download additional malware, and when info-stealing modules are used, it can collect user credentials in the infected system.
Usually, Amadey is installed by SmokeLoader which is distributed in the disguise of normal programs and crack malware. In the recent days, however, Amadey is being distributed to corporate users through malicious document files attached to spam mails and being used to install LockBit ransomware.
The confirmed C&C server URLs are as follows.
Top 4 – Guloader
GuLoader, which ranked fourth place with 9.8%, 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 Infostealers (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.
- Lplanters Paralleluniversers.exe
- Zoologens Lsningen.exe
Top 5 – Lokibot
Lokibot malware ranked fifth place with 6.8%. It is an Infostealer that leaks information about programs such as web browsers, email clients, and FTP clients.
Being a malware type that is distributed through spam emails, it shares similar file names with other malware spam emails.
As shown below, most Lokibot C&C server URLs tend to end in fre.php.
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