Analysis by: Alvin John Nieto
ALIASES:

Trojan:WinNT/Necurs.A (Microsoft), Troj/Necurs-BD (Sophos), Win32/TrojanDownloader.Necurs.A trojan (ESET)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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 may be dropped by other malware.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 60,416 bytes
File Type: SYS
Memory Resident: Yes
Initial Samples Received Date: 27 Feb 2014
Payload: Terminates processes

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.

It may be dropped by the following malware:

  • TSPY_ZBOT.TYZAR
  • TSPY_ZBOT.EFNA

Installation

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

  • %System%\drivers\{random}.sys

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Rootkit Capabilities

This Trojan is used by other malware for its rootkit functionalities.

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

This Trojan disables services used by the following companies by modifying its code to return to unsuccessful status:

  • Agnitum Ltd
  • ALWIL Software
  • PC Tools
  • GRISOFT, s.r.o.
  • Avira GmbH
  • BITDEFENDER LLC
  • BitDefender SRL
  • Comodo Inc
  • Doctor Web Ltd
  • ESET, spol. s r.o.
  • FRISK Software International Ltd
  • Kaspersky Lab
  • Panda Software International
  • Check Point Software Technologies Ltd
  • BullGuard Ltd
  • antimalware
  • NovaShield Inc
  • CJSC Returnil Software
  • Anti-Virus
  • Sophos Plc
  • Comodo Security Solutions
  • Quick Heal Technologies
  • G DATA Software
  • Beijing Rising
  • Immunet Corporation
  • K7 Computing
  • Sunbelt Software
  • SUNBELT SOFTWARE
  • Beijing Jiangmin
  • VirusBuster Ltd
  • KProcessHacker

This Trojan disables drivers with the following names by modifying its code to return to unsuccessful status:

  • eeCtrl.sys
  • eraser.sys
  • SRTSP.sys
  • SRTSPIT.sys
  • SRTSP64.SYS
  • a2gffx86.sys
  • a2gffx64.sys
  • a2gffi64.sys
  • a2acc.sys
  • a2acc64.sys
  • mbam.sys
  • eamonm.sys
  • MaxProtector.sys
  • SDActMon.sys
  • tmevtmgr.sys
  • tmpreflt.sys
  • vcMFilter.sys
  • drivesentryfilterdriver2lite.sys
  • mpFilter.sys
  • PSINPROC.SYS
  • PSINFILE.SYS
  • amfsm.sys
  • amm8660.sys
  • amm6460.sys
  • caavFltr.sys
  • ino_fltr.sys
  • avmf.sys
  • PLGFltr.sys
  • AshAvScan.sys
  • csaav.sys
  • SegF.sys
  • eeyehv.sys
  • eeyehv64.sys
  • NovaShield.sys
  • BdFileSpy.sys
  • tkfsft.sys
  • tkfsft64.sys
  • tkfsavxp.sys
  • tkfsavxp64.sys
  • SMDrvNt.sys
  • ATamptNt.sys
  • V3Flt2k.sys
  • V3MifiNt.sys
  • V3Ift2k.sys
  • V3IftmNt.sys
  • ArfMonNt.sys
  • AhnRghLh.sys
  • AszFltNt.sys
  • OMFltLh.sys
  • V3Flu2k.sys
  • vcdriv.sys
  • vcreg.sys
  • vchle.sys
  • NxFsMon.sys
  • AntiLeakFilter.sys
  • NanoAVMF.sys
  • shldflt.sys
  • nprosec.sys
  • nregsec.sys
  • issregistry.sys
  • THFilter.sys
  • pervac.sys
  • avgmfx86.sys
  • avgmfx64.sys
  • avgmfi64.sys
  • avgmfrs.sys
  • fortimon2.sys
  • fortirmon.sys
  • fortishield.sys
  • savonaccess.sys
  • OADevice.sys
  • pwipf6.sys
  • EstRkmon.sys
  • EstRkr.sys
  • dwprot.sys
  • Spiderg3.sys
  • STKrnl64.sys
  • UFDFilter.sys
  • SCFltr.sys
  • fildds.sys
  • fsfilter.sys
  • fpav_rtp.sys
  • cwdriver.sys
  • Rtw.sys
  • HookSys.sys
  • snscore.sys
  • ssvhook.sys
  • strapvista.sys
  • strapvista64.sys
  • sascan.sys
  • savant.sys
  • vradfil2.sys
  • fsgk.sys
  • PCTCore64.sys
  • PCTCore.sys
  • ikfilesec.sys
  • ZxFsFilt.sys
  • antispyfilter.sys
  • PZDrvXP.sys
  • ggc.sys
  • catflt.sys
  • kmkuflt.sys
  • mfencoas.sys
  • mfehidk.sys
  • cmdguard.sys
  • K7Sentry.sys
  • nvcmflt.sys
  • issfltr.sys
  • AVCKF.SYS
  • bdfsfltr.sys
  • bdfm.sys
  • AVC3.SYS
  • aswmonflt.sys
  • HookCentre.sys
  • PktIcpt.sys
  • MiniIcpt.sys
  • avgntflt.sys
  • klbg.sys
  • kldback.sys
  • kldlinf.sys
  • kldtool.sys
  • klif.sys
  • lbd.sys
  • rvsmon.sys
  • ssfmonm.sys
  • KmxAgent.sys
  • KmxAMRT.sys
  • KmxAMVet.sys
  • KmxStart.sys
  • ahnflt2k.sys
  • AhnRec2k.sys
  • AntiyFW.sys
  • v3engine.sys
  • Vba32dNT.sys
  • kprocesshacker.sys

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.670.07
FIRST VSAPI PATTERN DATE: 17 Mar 2014
VSAPI OPR PATTERN File: 10.671.00
VSAPI OPR PATTERN Date: 18 Mar 2014

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Scan your computer with your Trend Micro product and note files detected as RTKT_NECURS.BGSF

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as RTKT_NECURS.BGSF

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RTKT_NECURS.BGSF. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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