TROJ_NITOL.BE

 Analysis by: Nikko Tamana

 ALIASES:

Mal/Emogen-Y (Sophos), W32/Torr.BG!tr.bdr (Fortinet), W32/QQhelper.C.gen!Eldorado (FProt), Backdoor.Win32.Inject (Ikarus), Trojan:Win32/Nitol.B (Microsoft), a variant of Win32/ServStart.AD trojan (NOD32), Trojan.Dropper (Norton), Trojan.Win32.Generic!BT (Sunbelt), Gen:Variant.Barys.1424 (Bitdefender)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

It executes then deletes itself afterward.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats.

  TECHNICAL DETAILS

File Size:

51,568 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

17 Sep 2012

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %System%\{random file name}.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It executes then deletes itself afterward.

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\{random}\Parameters
ServiceDll = "%System%\{random filename}.dll"

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\{random}
Description = "netsvcs_0x0aaaaaaaaaaaaaaaaaaa"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\{random}\Parameters
ServiceMain = "StartRouter"

Download Routine

This Trojan connects to the following malicious URLs:

  • {BLOCKED}.{BLOCKED}.175.208