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 15th, 2023 (Monday) to May 21st, 2023 (Sunday).
For the main category, Infostealer ranked top with 43.8%, followed by downloader with 36.9%, backdoor with 15.3%, ransomware with 3.4%, and CoinMiner with 0.6%.
Top 1 – Amadey
This week, Amadey Bot ranked first place with 25.6%. 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 URL is as follows.
Top 2 – AgentTesla
AgentTesla is an Infostealer that ranked second place with 23.9%. 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 or Telegram API. The C&C information of recently collected samples is as follows.
- SMTP Server: mail.garagerobert[.]be
- SMTP Server: us2.smtp.mailhostbox[.]com
- Telegram API: hxxps://api.telegram[.]org/bot2134979594:AAFk4QkrlHlt2a-q-EhIoHZBbzxSH0QxiBI/
- Telegram API: hxxps://api.telegram[.]org/bot5515611206:AAEcQSX8hXHOAxSYr8KUdLxGF5eqw4FRXoA/
- Telegram API: hxxps://api.telegram[.]org/bot2062652208:AAEyc-7xEcUOQxNpdlexOidqQZT1Fi23E0A/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.
- INVOICE 4570.exe
- order details.scr
- Order No. I20220052.exe
- Purchase order.exe
- Sales Invoice.exe
- Shipping Details_PDF.exe
- SHIPPING DOCUMENTS.exe
- swift copy.exe
Top 3 – Formbook
Formbook ranked third place with 8.5%.
Like other Infostealers, it is mainly distributed through spam emails. The distributed file names are close to each other.
- May New-Order #Brazil-098484OBZ.exe
- prod sheet& Specs.exe
- PURCHASE INQUIRY for 151#PDF___________________..exe
- Request for Quotation_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 4 – Guloader
GuLoader, which ranked fourth place with 6.8%, 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.
- Tax Invoice -유아이 베트남 6월 SHIP.exe
- 7759303436-Tax Invoice.exe
- Udeladelsestegnets Skiascopy.exe
Top 5 – Lokibot
Lokibot malware ranked fifth place with 5.7%. 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.
As shown below, most Lokibot C&C server URLs tend to end in fre.php.
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