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 8th, 2023 (Monday) to May 14th, 2023 (Sunday).
For the main category, Infostealer ranked top with 49.8%, followed by downloader with 37.3%, backdoor with 11.0%, ransomware with 1.4%, and CoinMiner with 0.5%.
Top 1 – Amadey
This week, Amadey Bot ranked first place with 25.8%. 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 2 – AgentTesla
AgentTesla is an Infostealer that ranked second place with 24.9%. 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: sarahfoils.com
- SMTP Server: webmail.elpl.com.pk
- Telegram API: hxxps://api.telegram[.]org/bot6179106618:AAFHXiPxIxIFQ61pOBYbQQVUtpm03rgPe70/
- Telegram API: hxxps://api.telegram[.]org/bot5515611206:AAEcQSX8hXHOAxSYr8KUdLxGF5eqw4FRXoA/
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.
- 44XYZ_S Quote.exe
- New Order.exe
- Se adjunta factura proforma.exe
- Payment 20230504_1306030770.exe
- LC# 55040-2023 OFI.exe
Top 3 – Formbook
Formbook ranked third place with 9.1%.
Like other Infostealers, it is mainly distributed through spam emails. The distributed file names are close to each other.
- Inquiry No. MKP-ASL-RT-990821-02_pdf.exe
- PORT OUTSTANDINGS.exe
- New Order – Sample Request.iso
- Wire Instruction P85793.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 8.6%, 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.
- hxxp://194.59.218[.]151/jtTfvQt56.bin hxxp://priexports.com/wp-includes/aaxcdcm/UuDhBPJh120.bin
- hxxps://secr.[i]n/gallery/oo_PpROrG11.bin hxxp://126.96.36.199/UbtEVVkWDjTFGUv95.bin
- hxxp://194.87.151[.]30/OpgKnwoQwyHwIZTLfX129.bin hxxps://drive.google.com/uc?export=download&id=1FiIw3jOi2X6k7bk0O-0jJUtvYtEAKPJN
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.
- Joniseres Bremselngdens.exe
- Saddlers Hopefulnesses.exe
Top 5 – SnakeKeylogger
Taking fourth with 7.7%, SnakeKeylogger is an Infostealer that leaks information such as user key inputs, system clipboards, and browser account information.
Like AgentTesla, this malware uses email servers and user accounts when leaking collected information. Aside from these, FTP, Telegram, and discord can also be used. The following is the C&C information used by recently collected samples.
- SMTP Server: smtp.gmail.com
- Telegram API: hxxps://api.telegram[.]org/bot5830566856
- Telegram API: hxxps://api.telegram[.]org/bot6136035762
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