The ASEC analysis team is using the ASEC automatic analysis system RAPIT to categorize and respond to known malware. This post will list weekly statistics collected from October 10th, 2022 (Monday) to October 16th, 2022 (Sunday).
For the main category, downloader ranked top with 44.4%, followed by info-stealer with 41.7%, backdoor with 12.5%, ransomware with 0.9%, and CoinMiner with 0.5%.
Smokeloader is infostealer / downloader malware that is distributed via exploit kits. This week, it ranked first place with 18.1%. Like other malware that is distributed via exploit kits, this malware also has MalPe form.
When executed, it injects itself to explorer.exe, and the actual malicious behavior is executed by explorer.exe. After connecting to C&C server, it can either download additional module, or download another malware. Additionally downloaded malware usually has a feature of infostealer, and explorer.exe (child process) is created and injects module to operate.
For an analysis report related to Smoke Loader, refer to the ASEC Report below.
The confirmed C&C server URLs are as follows.
AgentTesla is an infostealer that ranked second place with 16.2%. It is an info-stealer that leaks user credentials saved in web browsers, emails, and FTP clients.
- server : ail.pisc[.]lk (108.170.60[.]107)
sender : sales@pisc[.]lk
receiver : decencykelvin4@gmail[.]com
user : sales@pisc[.]lk
pw : Pis******21
- server : mail.yesilcarsi[.]com (185.15.41[.]175)
sender : yesilcarsi@yesilcarsi[.]com
receiver : yesilcarsi@yesilcarsi[.]com
user : yesilcarsi@yesilcarsi[.]com
pw : Yc****60
- server : mail.irw.com[.]br (200.219.229[.]6)
sender : email@example.com[.]br
receiver : purchase@technospeedglobal[.]com
user : firstname.lastname@example.org[.]br
pw : Ev*****0@asecsecurityanalysisteam
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.
GuLoader, which ranked third place with 13.9%, 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 infostealer (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.
BeamWinHTTP is a downloader malware that ranked fourth with 12.5%. BeamWinHTTP 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.
Formbook ranked fifth place with 8.8%.
Like other info-stealer, it is mainly distributed through spam emails. The distributed file names are close to each other.
- shipping document_pdf.exe
Formbook is injected into normal processes (one is a running explorer.exe and the other is in system32) that perform malicious behaviors. 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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