Analysis by: Jon Dexter Laurin
ALIASES:

Backdoor:Win32/Vawtrak!rfn (Microsoft); HEUR:Trojan.Win32.Generic (Kaaspersky); Trojan.Gen.SMH.2 (Norton); a variant of Win32/Kryptik.DIST trojan (ESET-NOD32); Trojan.Win32.Crypt (Ikarus); Trojan horse Crypt4.PTC (AVG); Gen:Variant.Kazy.596661 (BitDefender)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 303,104 bytes
File Type: DLL
Initial Samples Received Date: 27 Jul 2015

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor drops the following copies of itself into the affected system:

  • %All Users Profile%\Application Data\{Random Name}\{Random Name}.{Random 3 Character} - for Windows XP and Lower
  • %All Users Profile%\{Random Name}\{Random Name}.{Random 3 Character} - for Windows Vista and Higher

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Name} = "regsvr32.exe "%All Users Profile%\Application Data\{Random Name}\{Random Name}.{Random 3 Characters}"" - For Windows XP and below

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Name} = "regsvr32.exe "%All Users Profile%\{Random Name}\{Random Name}.{Random 3 Characters}"" - For Windows Vista and above

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\{CLSID}

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
TabProcGrowth = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
2500 = "3"

HKEY_CURRENT_USER\Software\{CLSID}
{Random Name} = "{Hex Value}"

HKEY_CURRENT_USER\Software\{CLSID}
{Random Name 2} = "{Random Hex Values}"

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}ountrygor.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}orestmonth.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}wart.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}lace.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}rthgom.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}ornet.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}vertnom.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}esrest.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}first.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}o.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}e.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}n.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}i.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}s.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}isjohn.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}tehed.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}grigh.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}forrep.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}s.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}maheg.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}ec.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}arab.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}t.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}t.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}onsit.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}nate.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}shersgot.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}nhem.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}trow.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}natel.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}stargon.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}wler.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}arme.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}sterman.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}etlist.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}tu.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}nclis.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}valyf.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}oxyfe.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}tah.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}d.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}hmeligh.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}netons.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}ofreb.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}rowrab.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}rkeun.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}whanin.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}didnbe.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}enrit.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}fret.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}idti.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}arrep.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}tinbu.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}bonot.ru/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}athere.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}tdowen.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}reenh.com/stats/00/counter/0000006E/{random value}
  • http://{BLOCKED}home.com/stats/00/counter/0000006E/{random value}