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 June 5th, 2023 (Monday) to June 11th, 2023 (Sunday).
For the main category, Infostealer ranked top with 44.6%, followed by downloader with 43.9%, backdoor with 9.5%, and ransomware with 2.0%.
Top 1 – Amadey
This week, Amadey Bot ranked first place with 30.4%. 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 recent days, however, Amadey is being distributed to corporate users through malicious document files attached to spam emails and being used to install LockBit ransomware.
The confirmed C&C server URLs are as follows.
Top 2 – AgentTesla
AgentTesla is an Infostealer that ranked second place with 26.4%. It leaks user credentials saved in web browsers, emails, and FTP clients.
Although it uses emails (a.k.a. SMTP protocol) to leak collected information, there are samples that used FTP, Discord Webhooks, Telegram API, etc. The C&C information of recently collected samples is as follows.
- SMTP Server: mail.marineclaimoffice[.]com
- SMTP Server: us2.smtp.mailhostbox[.]com
- Discord WebHooks: hxxps://discord[.]com/api/webhooks/1109078597697802400/N0FrBeH_8MDeAwQC9ABA0W42QcoAZqnFM0qJOcVUO9LPKp2yMw5W1mobQTkR7BtIa2e8
- Telegram API: hxxps://api.telegram[.]org/bot6118510930:AAGLmjz14DOBPW-OuVj-xMJhmBoGJAqv5to/sendDocument
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.
- Quotation Request.exe
- Order 467589.exe
- 33690120233531MES_S Quote.exe
- 40023540MES_S Quote.exe
- 5314 Statement 0013167791.exe
- New Order_xlsx.exe
- RFQ_PO 211436 for Weatherbeeta pdf.exe
- SOLICITUD DE PRESUPUESTO 08062023.exe
Top 3 – Guloader
GuLoader, which ranked third place with 12.8%, 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.
- RFQ#84839_A2023_TEXHONG_TAN CANG_SAMPLES_PRODUCTS.exe
- Sgevindue Formateringsproblemets.exe
Top 4 – Lokibot
Lokibot malware ranked fourth place with 8.8%. It is an Infostealer that leaks information about programs such as web browsers, email clients, and FTP clients.
Being a malware that is distributed through spam emails, it shares similar file names with other malware spam emails.
- 140300838898 JAYA SENTOSA.exe
- DHL Express_#AWB.exe
- DHL Receipt_6005195460.exe
- FedEx Shipping Documents.exe
- Maersk Line Shipping documents.exe
As shown below, most Lokibot C&C server URLs tend to end in fre.php.
Top 5 – Formbook
Formbook ranked fifth place with 5.4%.
Like other Infostealers, it is mainly distributed through spam emails. The distributed file names are close to each other.
- PORTUGAL ORDER FOR JULY SALES PO#10-PAM USD.exe
- Purchase Order RFQ# 10075311 USD.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.
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