Threat Descriptions

Delf.AUY

Classification

Category :

Malware

Type :

Trojan-Downloader

Platform :

W32

Aliases :

Delf.AUY

Summary

Delf.AUY is a Borland Delphi complied malware that uses Internet Explorer to download and execute 5 other password stealing malware applications. Please see the details section for more information.

Removal

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Once Delf.AUY is executed, it will install itself by creating a copy in the system directory as intenat.exe. It uses a temporary batch file dropped in the system directory with a filename of Deleteme.bat to delete the executed copy of itself.

Delf.AUY creates the following registry entry to enable its execution automatic upon boot up:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] @ = %sysdir%\intenat.exe

After the malware installs, it will then start executing its download routine. Delf.AUY searches for the installation path of Internet Explorer from the following registry entry and uses it to download some password stealing trojans:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\App Paths\IEXPLORE.EXE]

If it has no value it will set it to the following hardcoded path and filename:

  • C:\Program Files\Internet Explorer\IEXPLORE.EXE

Below is a list of the URLs from where it will attempt to download other malware:

  • https://www.ac66.cn/down/[BLOCKED]ezi.exe detected as Trojan-PSW.Win32.Delf.pw
  • https://www.ac66.cn/down/[BLOCKED]hxy.exe detected as Trojan-PSW.Win32.WOW.de
  • https://www.ac66.cn/down/[BLOCKED]ichong.exe detected as Trojan-PSW.Win32.Delf.px
  • https://www.ac66.cn/down/[BLOCKED]q.exe detected as Trojan-PSW.Win32.QQRob.hw
  • https://www.ac66.cn/down/[BLOCKED]x.exe detected as Trojan-PSW.Win32.Lmir.bac

Delf.AUY will save and execute the downloads to these hardcoded path and filenames:

  • C:\program files\system.exe
  • C:\program files\system2.exe
  • C:\program files\system3.exe
  • C:\program files\system4.exe
  • C:\program files\system5.exe