BKDR_NECURS.A

January 16, 2013
 Analysis by: Michael Cabel
 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:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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.

However, as of this writing, the said sites are inaccessible.

It hides files, processes, and/or registry entries.

  TECHNICAL DETAILS

File Size:

97,792 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Jan 2013

Payload:

Connects to URLs/IPs, Hides files and processes

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 file(s)/component(s):

  • %System%\drivers\{Random Numbers}.sys - also detected as BKDR_NECURS.A

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

Autostart Technique

This backdoor 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\CurrentControlSet\
Services\{Malware File Name}

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}.{BLOCKED}.214.54/i.php
  • http://{BLOCKED}.{BLOCKED}.106.135/mac/mac.php

However, as of this writing, the said sites are inaccessible.

Rootkit Capabilities

This backdoor hides files, processes, and/or registry entries.

NOTES:

This backdoor monitors the affected system's registry to prevent access and/or removal of its added registry entries. It also monitors security-related applications from the following companies and prevents them from executing properly:

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

It does this by preventing the following files from loading to allow it to perform its routine:

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

  SOLUTION

Minimum Scan Engine:

9.300

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

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • {Malware File Name}

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_NECURS.A. 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.

NOTES:

Please perform the following as the second step of the solution:

Since this malware disables AV function, use Trend Micro’s Rescue Disk to identify and delete the malware. Take note of the file name of the identified malware for the next step.


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