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RTKT_NECURS.B
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes

Overview


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

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.

Technical Details


File size: 33,408 bytes
File type: SYS
Memory resident: Yes
Initial samples received date: 20 May 2014
Payload: Disables services

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:

  • BKDR_NECURS.BGSJ

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.)

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\CurrentControlSet\
Services\{random}
DisplayName = "{random}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Group = "Boot Bus Extender"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
ImagePath = "%System%\drivers\{random}.sys"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Start = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Tag = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Type = "1"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}

Rootkit Capabilities

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

NOTES:

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

  • ALWIL Software
  • Agnitum Ltd
  • Anti-Virus
  • Avira GmbH
  • BITDEFENDER LLC
  • Beijing Jiangmin
  • Beijing Rising
  • BitDefender SRL
  • BullGuard Ltd
  • CJSC Returnil Software
  • Check Point Software Technologies Ltd
  • Comodo Inc
  • 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
  • KProcessHacker
  • Kaspersky Lab
  • NovaShield Inc
  • PC Tools
  • Panda Software International
  • Quick Heal Technologies
  • SUNBELT SOFTWARE
  • Sophos Plc
  • Sunbelt Software
  • VirusBuster Ltd
  • WinDefend

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

  • 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

It has anti-virtual machine routine that causes virtual machines to hang.

Solution


Minimum scan engine: 9.700
First VSAPI Pattern File: 10.806.04
First VSAPI Pattern Release Date: 20 May 2014
VSAPI OPR Pattern Version: 10.807.00
VSAPI OPR Pattern Release Date: 20 May 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.B

Step 3

Restart in Safe Mode

[ Learn more ]

Step 4

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
    • {random}

Step 5

Search and delete files detected as RTKT_NECURS.B

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

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RTKT_NECURS.B. 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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Analysis By: Al Victor de Leon

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