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 April 10th, 2023 (Monday) to April 16th, 2023 (Sunday).
For the main category, backdoor ranked top with 58.4%, followed by downloader with 23.0%, Infostealer with 17.2%, ransomware with 0.8%, and banking with 0.6%.
Top 1 – RedLine
RedLine ranked first place with 54.7%. The malware steals various information such as web browsers, FTP clients, cryptocurrency wallets, and PC settings. It can also download additional malware by receiving commands from the C&C server. Like BeamWinHTTP, there have been numerous cases of RedLine being distributed under the disguise of a software crack file.
The following are the confirmed C&C server domains for RedLine:
Top 2 – Amadey
This week, Amadey Bot ranked second place with 15.7%. 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 3 – AgentTesla
AgentTesla is an Infostealer that ranked third place with 10.8%. 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 : smtp.nutiribio.com
User : email@example.com
Password : zG****l5
Receiver : firstname.lastname@example.org
- SMTP Server : mail.sonic.net
User : email@example.com
Password : KA*******ELU
Receiver : firstname.lastname@example.org
- Telegram API : hxxps://api.telegram[.]org/bot1611551445:AAFDJ3yQMlB3zXJGib2_TFkq1jedBMj3GTw
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.
- ARH PO # 2301433.exe
- DETAILS AND INVOICES 4.exe
- Advanced Payment – Ref_001299384596OBR11522.exe
- DHL AWB – Invoice & Shipping Documents.exe
Top 4 – BeamWinHTTP
BeamWinHTTP is a downloader malware that ranked fourth with 3.1%. The malware is distributed via malware disguised as PUP installer. When it is executed, it installs PUP malware Garbage Cleaner and can download and install additional malware at the same time.
The confirmed C&C server URL is as follows.
Top 5 – Formbook
Formbook ranked fifth place with 2.7%.
Like other Infostealers, it is mainly distributed through spam emails. The distributed file names are close to each other.
- List Items.exe
- Deposit slip.exe
- statement for HADCO S.A.O.C.exe
- FTT 325272022023.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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