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RTKT_NECURS.MJYE
Aliases: Troj/Necurs-CA (Sophos) ,Trojan horse Hider.YTT (AVG) ,W32/Qhost.O2.gen!Eldorado (generic, not disinfectable) (Fprot) ,Rootkit:Necurs (Ikarus) ,Rootkit.Win32.Necurs.iy (Kaspersky) ,Trojan:WinNT/Necurs.A (Microsoft) ,Win32/TrojanDownloader.Necurs.A trojan (Eset) ,Trojan.Win32.Generic!BT (Sunbelt)
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)
In the wild: Yes

Overview


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

This malware is the final payload of the ZeuS variant that uses random headers to make detection difficult.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

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: 33,920 bytes
File type: SYS
Memory resident: Yes
Initial samples received date: 01 Jun 2014
Payload: Hooks APIs

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.YUYET

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"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Db0 = "{Hex Values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Db1 = "{Hex Values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Db2 = "{Hex Values}"

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}

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{Service under 'Boot Bus Extender Group'}
Tag = "{IValue+1}"

(Note: The default value data of the said registry entry is "{Value}".)

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

It disables loaded and new drivers with the following file name by patching its 'DriverEntry' to return STATUS_UNSUCCESSFUL:

  • 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

It disables loaded and new drivers with the following Vendor Name by patching its 'DriverEntry' to return STATUS_UNSUCCESSFUL:

  • 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
  • Symantec Corporation
  • 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

It hooks the following APIs:

  • NtOpenProcess
  • NtOpenThread

Solution


Minimum scan engine: 9.700
First VSAPI Pattern File: 10.840.02
First VSAPI Pattern Release Date: 04 Jun 2014
VSAPI OPR Pattern Version: 10.841.00
VSAPI OPR Pattern Release Date: 04 Jun 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

Remove malware/grayware files that dropped/downloaded RTKT_NECURS.MJYE. (Note: Please skip this step if the threats listed below have already been removed.)

Step 3

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

Step 4

Restart in Safe Mode

[ Learn more ]

Step 5

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 6

Search and delete files detected as RTKT_NECURS.MJYE

[ 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 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RTKT_NECURS.MJYE. 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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