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Microsoft Security

The five-day job: A BlackByte ransomware intrusion case study

As ransomware attacks continue to grow in number and sophistication, threat actors can quickly impact business operations if organizations are not well prepared. In a recent investigation by Microsoft Incident Response (previously known as Microsoft Detection and Response Team – DART) of an intrusion, we found that the threat actor progressed through the full attack chain, from initial access to impact, in less than five days, causing significant business disruption for the victim organization.

Our investigation found that within those five days, the threat actor employed a range of tools and techniques, culminating in the deployment of BlackByte 2.0 ransomware, to achieve their objectives. These techniques included:

BlackByte 2.0 ransomware attack chain by order of stages: initial access and privilege escalation, persistence and command and control, reconnaissance, credential access, lateral movement, data staging and exfiltration, and impact.
Figure 1. BlackByte 2.0 ransomware attack chain

In this blog, we share details of our investigation into the end-to-end attack chain, exposing security weaknesses that the threat actor exploited to advance their attack. As we learned from Microsoft’s tracking of ransomware attacks and the cybercriminal economy that enables them, disrupting common attack patterns could stop many of the attacker activities that precede ransomware deployment. This case highlights that common security hygiene practices go a long way in preventing, identifying, and responding to malicious activity as early as possible to mitigate the impact of ransomware attacks. We encourage organizations to follow the outlined mitigation steps, including ensuring that internet-facing assets are up to date and configured securely. We also share indicators of compromise, detection details, and hunting guidance to help organizations identify and respond to these attacks in their environments.  

Forensic analysis

Initial access and privilege escalation

To obtain initial access into the victim’s environment, the threat actor was observed exploiting the ProxyShell vulnerabilities CVE-2021-34473, CVE-2021-34523, and CVE-2021-31207 on unpatched Microsoft Exchange Servers. The exploitation of these vulnerabilities allowed the threat actor to:

The threat actor was observed operating from the following IP to exploit ProxyShell and access the web shell:

Persistence

Backdoor

After gaining access to a device, the threat actor created the following registry run keys to run a payload each time a user signs in:

Registry keyValue nameValue data
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run  MsEdgeMsErundll32 C:\Users\user\Downloads\api-msvc.dll,Default  
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run  MsEdgeMsErundll32 C:\temp\api-msvc.dll,Default  
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run  MsEdgeMsErundll32 C:\systemtest\api-system.png,Default

The file api-msvc.dll (SHA-256: 4a066569113a569a6feb8f44257ac8764ee8f2011765009fdfd82fe3f4b92d3e) was determined to be a backdoor capable of collecting system information, such as the installed antivirus products, device name, and IP address. This information is then sent via HTTP POST request to the following C2 channel:

The organization was not using Microsoft Defender Antivirus, which detects this malware as Trojan:Win32/Kovter!MSR, as the primary antivirus solution, and the backdoor was allowed to run.

An additional file, api-system.png, was identified to have similarities to api-msvc.dll. This file behaved like a DLL, had the same default export function, and also leveraged run keys for persistence.

Cobalt Strike Beacon

The threat actor leveraged Cobalt Strike to achieve persistence. The file sys.exe (SHA-256: 5f37b85687780c089607670040dbb3da2749b91b8adc0aa411fd6280b5fa7103), detected by Microsoft Defender Antivirus as Trojan:Win64/CobaltStrike!MSR, was determined to be a Cobalt Strike Beacon and was downloaded directly from the file sharing service temp[.]sh:

This beacon was configured to communicate with the following C2 channel:

AnyDesk

Threat actors leverage legitimate remote access tools during intrusions to blend into a victim network. In this case, the threat actor utilized the remote administration tool AnyDesk, to maintain persistence and move laterally within the network. AnyDesk was installed as a service and was run from the following paths:

Successful connections were observed in the AnyDesk log file ad_svc.trace involving anonymizer service IP addresses linked to TOR and MULLVAD VPN, a common technique that threat actors employ to obscure their source IP ranges.

Reconnaissance

We found the presence and execution of the network discovery tool NetScan being used by the threat actor to perform network enumeration using the following file names:

Additionally, execution of AdFind (SHA-256: f157090fd3ccd4220298c06ce8734361b724d80459592b10ac632acc624f455e), an Active Directory reconnaissance tool, was observed in the environment.

Credential access

Evidence of likely usage of the credential theft tool Mimikatzwas also uncovered through the presence of a related log file mimikatz.log. Microsoft IR assesses that Mimikatz was likely used to attain credentials for privileged accounts.

Lateral movement

Using compromised domain admin credentials, the threat actor used Remote Desktop Protocol (RDP) and PowerShell remoting to obtain access to other servers in the environment, including domain controllers.

Data staging and exfiltration

In one server where Microsoft Defender Antivirus was installed, a suspicious file named explorer.exe was identified, detected as Trojan:Win64/WinGoObfusc.LK!MT, and quarantined. However, because tamper protection wasn’t enabled on this server, the threat actor was able to disable the Microsoft Defender Antivirus service, enabling the threat actor to run the file using the following command:

explorer.exe P@$$w0rd

After reverse engineering explorer.exe, we determined it to be ExByte, a GoLang-based tool developed and commonly used in BlackByte ransomware attacks for collection and exfiltration of files from victim networks. This tool is capable of enumerating files of interest across the network and, upon execution, creates a log file containing a list of files and associated metadata. Multiple log files were uncovered during the investigation in the path:

Analysis of the binary revealed a list of file extensions that are targeted for enumeration.

Figure-2.-Binary-analysis-showing-file-extensions-enumerated-by-explorer.exe_
Figure 2. Binary analysis showing file extensions enumerated by explorer.exe

Forensic analysis identified a file named data.txt that was created and later deleted after ExByte execution. This file contained obfuscated credentials that ExByte leveraged to authenticate to the popular file sharing platform Mega NZ using the platform’s API at:

Figure 3. Binary analysis showing explorer.exe functionality for connecting to file sharing service MEGA NZ

We also determined that this version of Exbyte was crafted specifically for the victim, as it contained a hardcoded device name belonging to the victim and an internal IP address.

ExByte execution flow

Upon execution, ExByte decodes several strings and checks if the process is running with privileged access by reading \\.\PHYSICALDRIVE0:

After this access check, explorer.exe attempts to read the data.txt file in the current location:

C:\Windows\system32\cmd.exe /c ping 1.1.1.1 -n 10 > nul & Del <PATH>\explorer.exe /F /Q
{
	“a”:”us0”,
	“user”:”<CONTENT FROM data.txt>”
}

Finally, it forms a URL for sign-in to the API of the service MEGA NZ:

Data encryption and destruction

On devices where files were successfully encrypted, we identified suspicious executables, detected by Microsoft Defender Antivirus as Trojan:Win64/BlackByte!MSR, with the following names:

The files were analyzed and determined to be BlackByte 2.0 binaries responsible for encryption across the environment. The binaries require an 8-digit key number to encrypt files.

Two modes of execution were identified:

Depending on the switch (-s or -a), execution may create the following files:

BlackByte 2.0 ransomware capabilities

Some capabilities identified for the BlackByte 2.0 ransomware were:

Recommendations

To guard against BlackByte ransomware attacks, Microsoft recommends the following:

Conclusion

BlackByte ransomware attacks target organizations that have infrastructure with unpatched vulnerabilities.  As outlined in the Microsoft Digital Defense Report, common security hygiene practices, including keeping systems up to date, could protect against 98% of attacks.

As new tools are being developed by threat actors, a modern threat protection solution like Microsoft 365 Defender is necessary to prevent and detect the multiple techniques used in the attack chain, especially where the threat actor attempts to evade or disable specific defense mechanisms. Hunting for malicious behavior should be performed regularly in order to detect potential attacks that could evade detections, as a complementary activity for continuous monitoring from security tools alerts and incidents.

To understand how Microsoft can help you secure your network and respond to network compromise, visit https://aka.ms/MicrosoftIR.

Microsoft 365 Defender detections

Microsoft 365 Defender is becoming Microsoft Defender XDR. Learn more.

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects this threat as the following malware:

Microsoft Defender for Endpoint

The following alerts might indicate threat activity related to this threat. Note, however, that these alerts can be also triggered by unrelated threat activity.

Microsoft Defender Vulnerability Management

Microsoft Defender Vulnerability Management surfaces devices that may be affected by the following vulnerabilities used in this threat:

Hunting queries

Microsoft 365 Defender

Microsoft 365 Defender customers can run the following query to find related activity in their networks:

ProxyShell web shell creation events

DeviceProcessEvents
| where ProcessCommandLine has_any ("ExcludeDumpster","New-ExchangeCertificate") and ProcessCommandLine has_any ("-RequestFile","-FilePath")

Suspicious vssadmin events

DeviceProcessEvents
| where ProcessCommandLine has_any ("vssadmin","vssadmin.exe") and ProcessCommandLine has "Resize ShadowStorage" and ProcessCommandLine has_any ("MaxSize=401MB"," MaxSize=UNBOUNDED")

Detection for persistence creation using Registry Run keys

DeviceRegistryEvents 
| where ActionType == "RegistryValueSet" 
| where (RegistryKey has @"Microsoft\Windows\CurrentVersion\RunOnce" and RegistryValueName == "MsEdgeMsE")  
    or (RegistryKey has @"Microsoft\Windows\CurrentVersion\RunOnceEx" and RegistryValueName == "MsEdgeMsE")
    or (RegistryKey has @"Microsoft\Windows\CurrentVersion\Run" and RegistryValueName == "MsEdgeMsE")
| where RegistryValueData startswith @"rundll32"
| where RegistryValueData endswith @".dll,Default"
| project Timestamp,DeviceId,DeviceName,ActionType,RegistryKey,RegistryValueName,RegistryValueData

Microsoft Sentinel

Microsoft Sentinel customers can use the TI Mapping analytics (a series of analytics all prefixed with ‘TI map’) to automatically match the malicious domain indicators mentioned in this blog post with data in their workspace. If the TI Map analytics are not currently deployed, customers can install the Threat Intelligence solution from the Microsoft Sentinel Content Hub to have the analytics rule deployed in their Sentinel workspace. More details on the Content Hub can be found here:  https://learn.microsoft.com/azure/sentinel/sentinel-solutions-deploy

Microsoft Sentinel also has a range of detection and threat hunting content that customers can use to detect the post exploitation activity detailed in this blog in addition to Microsoft 365 Defender detections list above.

Indicators of compromise

The table below shows IOCs observed during our investigation. We encourage our customers to investigate these indicators in their environments and implement detections and protections to identify past related activity and prevent future attacks against their systems.

IndicatorTypeDescription
4a066569113a569a6feb8f44257ac8764ee8f2011765009fdfd82fe3f4b92d3eSHA-256api-msvc.dll (Backdoor installed through RunKeys)
5f37b85687780c089607670040dbb3da2749b91b8adc0aa411fd6280b5fa7103SHA-256sys.exe (Cobalt Strike Beacon)
01aa278b07b58dc46c84bd0b1b5c8e9ee4e62ea0bf7a695862444af32e87f1fdSHA-256rENEgOtiAtES (Vulnerable driver RtCore64.sys created by BlackByte binary)
ba3ec3f445683d0d0407157fda0c26fd669c0b8cc03f21770285a20b3133098fSHA-256[RANDOM_NAME].exe (UPX Packed PsExec created by BlackByte binary)
1b9badb1c646a19cdf101ac4f6fdd23bc61eaab8c9f925eb41848cea9fd0738eSHA-256“netscan.exe”, “netapp.exe (Netscan network discovery tool)
f157090fd3ccd4220298c06ce8734361b724d80459592b10ac632acc624f455eSHA-256AdFind.exe (Active Directory information gathering tool)
hxxps://myvisit[.]alteksecurity[.]org/tURLC2 for backdoor api-msvc.dll
hxxps://temp[.]sh/szAyn/sys.exeURLDownload URL for sys.exe
109.206.243[.]59IP AddressC2 for Cobalt Strike Beacon sys.exe
185.225.73[.]244IP AddressOriginating IP address for ProxyShell exploitation and web shell interaction

NOTE: These indicators should not be considered exhaustive for this observed activity.

Appendix

File extensions targeted by BlackByte binary for encryption:

.4dd.4dl.accdb.accdc.accde.accdr.accdt.accft
.adb.ade.adf.adp.arc.ora.alf.ask
.btr.bdf.cat.cdb.ckp.cma.cpd.dacpac
.dad.dadiagrams.daschema.db.db-shm.db-wal.db3.dbc
.dbf.dbs.dbt.dbv. dbx. dcb. dct. dcx
. ddl. dlis. dp1. dqy. dsk. dsn. dtsx. dxl
. eco. ecx. edb. epim. exb. fcd. fdb. fic
. fmp. fmp12. fmpsl. fol.fp3. fp4. fp5. fp7
. fpt. frm. gdb. grdb. gwi. hdb. his. ib
. idb. ihx. itdb. itw. jet. jtx. kdb. kexi
. kexic. kexis. lgc. lwx. maf. maq. mar. masmav
. mdb. mpd. mrg. mud. mwb. myd. ndf. nnt
. nrmlib. ns2. ns3. ns4. nsf. nv. nv2. nwdb
. nyf. odb. ogy. orx. owc. p96. p97. pan
. pdb. pdm. pnz. qry. qvd. rbf. rctd. rod
. rodx. rpd. rsd. sas7bdat. sbf. scx. sdb. sdc
. sdf. sis. spg. sql. sqlite. sqlite3. sqlitedb. te
. temx. tmd. tps. trc. trm. udb. udl. usr
. v12. vis. vpd. vvv. wdb. wmdb. wrk. xdb
. xld. xmlff. abcddb. abs. abx. accdw. and. db2
. fm5. hjt. icg. icr. kdb. lut. maw. mdn
. mdt       

Shared folders targeted for encryption (Example: \\[IP address]\Downloads):

UsersBackupVeeamhomeshome
mediacommonStorage ServerPublicWeb
ImagesDownloadsBackupDataActiveBackupForBusinessBackups
NAS-DCDCBACKUPDirectorFilesshare 

File extensions ignored:

.ini.url.msilog.log.ldf.lock.theme.msi
.sys.wpx.cpl.adv.msc.scr.key.ico
.dll.hta.deskthemepack.nomedia.msu.rtp.msp.idx
.ani.386.diagcfg.bin.mod.ics.com.hlp
 .spl.nls.cab.exe.diagpkg.icl.ocx.rom
.prf.thempack.msstyles.icns.mpa.drv.cur.diagcab
.cmd.shs      

Folders ignored:

windowsbootprogram files (x86)windows.oldprogramdata
intelbitdefendertrend microwindowsappsappdata
application datasystem volume informationperflogsmsocache 

Files ignored:

bootnxtntldrbootmgrthumbs.db
ntuser.datbootsect.bakautoexec.baticoncache.db
bootfont.bin   

Processes terminated:

teracopyteamviewernsservicensctrluranium
processhackerprocmonpestudioprocmon64x32dbg
x64dbgcff explorerprocexppslisttcpview
tcpvcondbgviewrammaprammap64vmmap
ollydbgautorunsautorunsscfilemonregmon
idaqidaq64immunitydebuggerwiresharkdumpcap
hookexplorerimportrecpetoolslordpesysinspector
proc_analyzersysanalyzersniff_hitwindbgjoeboxcontrol
joeboxserverresourcehackerfiddlerhttpdebuggerdumpit
rammaprammap64vmmapagntsvccntaosmgr
dbeng50dbsnmpencsvcinfopathisqlplussvc
mbamtraymsaccessmsftesqlmspubmydesktopqos
mydesktopservicemysqldmysqld-ntmysqld-optNtrtscan
ocautoupdsocommocssdonenoteoracle
outlookPccNTMonpowerpntsqbcoreservicesql
sqlagentsqlbrowsersqlservrsqlwritersteam
synctimetbirdconfigthebatthebat64thunderbird
tmlistenvisiowinwordwordpadxfssvccon
zoolz    

Services terminated:

CybereasonRansomFreevnetdbpcdSamSsTeraCopyService
msftesqlnsServiceklvssbridge64vapiendpointShMonitor
SmcinstSmcServiceSntpServicesvcGenericHostSwi_
TmCCSFtmlistenTrueKeyTrueKeySchedulerTrueKeyServiceHelper
WRSVCMcTaskManagerOracleClientCache80mfefirewbengine
mfemmsRESvcmfevtpsacsvrSAVAdminService
SepMasterServicePDVFSServiceESHASRVSDRSVCFA_Scheduler
KAVFSKAVFS_KAVFSGTkavfsslpklnagentmacmnsvc
masvcMBAMServiceMBEndpointAgentMcShieldaudioendpointbuilder
AntivirusAVPDCAgentbedbgEhttpSrv
MMSekrnEPSecurityServiceEPUpdateServicentrtscan
EsgShKernelmsexchangeadtopologyAcrSch2SvcMSOLAP$TPSAMAIntel(R) PROSet Monitoring
msexchangeimap4ARSMunistoresvc_1af40aReportServer$TPSMSOLAP$SYSTEM_BGC
W3SvcMSExchangeSRSReportServer$TPSAMAZoolz 2 ServiceMSOLAP$TPS
aphidmonitorserviceSstpSvcMSExchangeMTAReportServer$SYSTEM_BGCSymantec System Recovery
UI0DetectMSExchangeSAMSExchangeISReportServerMsDtsServer110
POP3SvcMSExchangeMGMTSMTPSvcMsDtsServerIisAdmin
MSExchangeESEraserSvc11710Enterprise Client ServiceMsDtsServer100NetMsmqActivator
stc_raw_agentVSNAPVSSPDVFSServiceAcrSch2SvcAcronis
CASAD2DWebSvcCAARCUpdateSvcMcAfeeavpsusDLPAgentService
mfewcBMR Boot ServiceDefWatchccEvtMgrccSetMgr
SavRoamRTVsc screenconnectransomsqltelemetrymsexch
vncteamviewermsolapveeambackup
sqlmemtasvsssophossvc$
mepocswuauserv   

Drivers that Blackbyte can bypass:

360avflt.sys360box.sys360fsflt.sys360qpesv.sys5nine.cbt.sys
a2acc.sysa2acc64.sysa2ertpx64.sysa2ertpx86.sysa2gffi64.sys
a2gffx64.sysa2gffx86.sysaaf.sysaalprotect.sysabrpmon.sys
accessvalidator.sysacdriver.sysacdrv.sysadaptivaclientcache32.sysadaptivaclientcache64.sys
adcvcsnt.sysadspiderdoc.sysaefilter.sysagentrtm64.sysagfsmon.sys
agseclock.sysagsyslock.sysahkamflt.sysahksvpro.sysahkusbfw.sys
ahnrghlh.sysaictracedrv_am.sysairship-filter.sysajfsprot.sysalcapture.sys
alfaff.sysaltcbt.sysamfd.sysamfsm.sysamm6460.sys
amm8660.sysamsfilter.sysamznmon.sysantileakfilter.sysantispyfilter.sys
anvfsm.sysapexsqlfilterdriver.sysappcheckd.sysappguard.sysappvmon.sys
arfmonnt.sysarta.sysarwflt.sysasgard.sysashavscan.sys
asiofms.sysaswfsblk.sysaswmonflt.sysaswsnx.sysaswsp.sys
aszfltnt.sysatamptnt.sysatc.sysatdragent.sysatdragent64.sys
aternityregistryhook.sysatflt.sysatrsdfw.sysauditflt.sysaupdrv.sys
avapsfd.sysavc3.sysavckf.sysavfsmn.sysavgmfi64.sys
avgmfrs.sysavgmfx64.sysavgmfx86.sysavgntflt.sysavgtpx64.sys
avgtpx86.sysavipbb.sysavkmgr.sysavmf.sysawarecore.sys
axfltdrv.sysaxfsysmon.sysayfilter.sysb9kernel.sysbackupreader.sys
bamfltr.sysbapfecpt.sysbbfilter.sysbd0003.sysbddevflt.sys
bdfiledefend.sysbdfilespy.sysbdfm.sysbdfsfltr.sysbdprivmon.sys
bdrdfolder.sysbdsdkit.sysbdsfilter.sysbdsflt.sysbdsvm.sys
bdsysmon.sysbedaisy.sysbemk.sysbfaccess.sysbfilter.sys
bfmon.sysbhdrvx64.sysbhdrvx86.sysbhkavka.sysbhkavki.sys
bkavautoflt.sysbkavsdflt.sysblackbirdfsa.sysblackcat.sysbmfsdrv.sys
bmregdrv.sysboscmflt.sysbosfsfltr.sysbouncer.sysboxifier.sys
brcow_x_x_x_x.sysbrfilter.sysbrnfilelock.sysbrnseclock.sysbrowsermon.sys
bsrfsflt.sysbssaudit.sysbsyaed.sysbsyar.sysbsydf.sys
bsyirmf.sysbsyrtm.sysbsysp.sysbsywl.sysbwfsdrv.sys
bzsenspdrv.sysbzsenth.sysbzsenyaradrv.syscaadflt.syscaavfltr.sys
cancelsafe.syscarbonblackk.syscatflt.syscatmf.syscbelam.sys
cbfilter20.syscbfltfs4.syscbfsfilter2017.syscbfsfilter2020.syscbsampledrv.sys
cdo.syscdrrsflt.syscdsgfsfilter.syscentrifyfsf.syscfrmd.sys
cfsfdrvcgwmf.syschange.syschangelog.syschemometecfilter.sys
ciscoampcefwdriver.sysciscoampheurdriver.sysciscosam.sysclumiochangeblockmf.syscmdccav.sys
cmdcwagt.syscmdguard.syscmdmnefs.syscmflt.syscode42filter.sys
codex.sysconduantfsfltr.syscontainermonitor.syscpavfilter.syscpavkernel.sys
cpepmon.syscrexecprev.syscrncache32.syscrncache64.syscrnsysm.sys
cruncopy.syscsaam.syscsaav.syscsacentr.syscsaenh.sys
csagent.syscsareg.syscsascr.syscsbfilter.syscsdevicecontrol.sys
csfirmwareanalysis.syscsflt.syscsmon.syscssdlp.sysctamflt.sys
ctifile.sysctinet.sysctrpamon.sysctx.syscvcbt.sys
cvofflineflt32.syscvofflineflt64.syscvsflt.syscwdriver.syscwmem2k64.sys
cybkerneltracker.syscylancedrv64.syscyoptics.syscyprotectdrv32.syscyprotectdrv64.sys
cytmon.syscyverak.syscyvrfsfd.syscyvrlpc.syscyvrmtgn.sys
datanow_driver.sysdattofsf.sysda_ctl.sysdcfafilter.sysdcfsgrd.sys
dcsnaprestore.sysdeepinsfs.sysdelete_flt.sysdevmonminifilter.sysdfmfilter.sys
dgedriver.sysdgfilter.sysdgsafe.sysdhwatchdog.sysdiflt.sys
diskactmon.sysdkdrv.sysdkrtwrt.sysdktlfsmf.sysdnafsmonitor.sys
docvmonk.sysdocvmonk64.sysdpmfilter.sysdrbdlock.sysdrivesentryfilterdriver2lite.sys
drsfile.sysdrvhookcsmf.sysdrvhookcsmf_amd64.sysdrwebfwflt.sysdrwebfwft.sys
dsark.sysdsdriver.sysdsfemon.sysdsflt.sysdsfltfs.sys
dskmn.sysdtdsel.sysdtpl.sysdwprot.sysdwshield.sys
dwshield64.syseamonm.syseaseflt.syseasyanticheat.syseaw.sys
ecatdriver.sysedevmon.sysednemfsfilter.sysedrdrv.sysedrsensor.sys
edsigk.syseectrl.syseetd32.syseetd64.syseeyehv.sys
eeyehv64.sysegambit.sysegfilterk.sysegminflt.sysegnfsflt.sys
ehdrv.syselock2fsctldriver.sysemxdrv2.sysenigmafilemondriver.sysenmon.sys
epdrv.sysepfw.sysepfwwfp.sysepicfilter.sysepklib.sys
epp64.sysepregflt.syseps.sysepsmn.sysequ8_helper.sys
eraser.sysesensor.sysesprobe.sysestprmon.sysestprp.sys
estregmon.sysestregp.sysestrkmon.sysestrkr.syseventmon.sys
evmf.sysevscase.sysexcfs.sysexprevdriver.sysfailattach.sys
failmount.sysfam.sysfangcloud_autolock_driver.sysfapmonitor.sysfarflt.sys
farwflt.sysfasdriverfcnotify.sysfcontrol.sysfdrtrace.sys
fekern.sysfencry.sysffcfilt.sysffdriver.sysfildds.sys
filefilter.sysfileflt.sysfileguard.sysfilehubagent.sysfilemon.sys
filemonitor.sysfilenamevalidator.sysfilescan.sysfilesharemon.sysfilesightmf.sys
filesystemcbt.sysfiletrace.sysfile_monitor.sysfile_protector.sysfile_tracker.sys
filrdriver.sysfim.sysfiometer.sysfiopolicyfilter.sysfjgsdis2.sys
fjseparettifilterredirect.sysflashaccelfs.sysflightrecorder.sysfltrs329.sysflyfs.sys
fmdrive.sysfmkkc.sysfmm.sysfortiaptfilter.sysfortimon2.sys
fortirmon.sysfortishield.sysfpav_rtp.sysfpepflt.sysfsafilter.sys
fsatp.sysfsfilter.sysfsgk.sysfshs.sysfsmon.sys
fsmonitor.sysfsnk.sysfsrfilter.sysfstrace.sysfsulgk.sys
fsw31rj1.sysgagsecurity.sysgbpkm.sysgcffilter.sysgddcv.sys
gefcmp.sysgemma.sysgeprotection.sysggc.sysgibepcore.sys
gkff.sysgkff64.sysgkpfcb.sysgkpfcb64.sysgofsmf.sys
gpminifilter.sysgroundling32.sysgroundling64.sysgtkdrv.sysgumhfilter.sys
gzflt.syshafsnk.syshbflt.syshbfsfltr.syshcp_kernel_acq.sys
hdcorrelatefdrv.syshdfilemon.syshdransomoffdrv.syshdrfs.sysheimdall.sys
hexisfsmonitor.syshfileflt.syshiofs.syshmpalert.syshookcentre.sys
hooksys.syshpreg.syshsmltmon.syshsmltwhl.syshssfwhl.sys
hvlminifilter.sysibr2fsk.sysiccfileioad.sysiccfilteraudit.sysiccfiltersc.sys
icfclientflt.sysicrlmonitor.sysiderafilterdriver.sysielcp.sysieslp.sys
ifs64.sysignis.sysiguard.sysiiscache.sysikfilesec.sys
im.sysimffilter.sysimfilter.sysimgguard.sysimmflex.sys
immunetprotect.sysimmunetselfprotect.sysinisbdrv64.sysino_fltr.sysintelcas.sys
intmfs.sysinuse.sysinvprotectdrv.sysinvprotectdrv64.sysionmonwdrv.sys
iothorfs.sysipcomfltr.sysipfilter.sysiprotect.sysiridiumswitch.sys
irongatefd.sysisafekrnl.sysisafekrnlmon.sysisafermonisecureflt.sys
isedrv.sysisfpdrv.sysisirmfmon.sysisregflt.sysisregflt64.sys
issfltr.sysissregistry.sysit2drv.sysit2reg.sysivappmon.sys
iwdmfs.sysiwhlp.sysiwhlp2.sysiwhlpxp.sysjdppsf.sys
jdppwf.sysjkppob.sysjkppok.sysjkpppf.sysjkppxk.sys
k7sentry.syskavnsi.syskawachfsminifilter.syskc3.syskconv.sys
kernelagent32.syskewf.syskfac.syskfileflt.syskisknl.sys
klam.sysklbg.sysklboot.syskldback.syskldlinf.sys
kldtool.sysklfdefsf.sysklflt.sysklgse.sysklhk.sys
klif.sysklifaa.sysklifks.sysklifsm.sysklrsps.sys
klsnsr.sysklupd_klif_arkmon.syskmkuflt.syskmnwch.syskmxagent.sys
kmxfile.syskmxsbx.sysksfsflt.sysktfsfilter.sysktsyncfsflt.sys
kubwksp.syslafs.syslbd.syslbprotect.syslcgadmon.sys
lcgfile.syslcgfilemon.syslcmadmon.syslcmfile.syslcmfilemon.sys
lcmprintmon.sysldsecdrv.syslibwamf.syslivedrivefilter.sysllfilter.sys
lmdriver.syslnvscenter.syslocksmith.syslragentmf.syslrtp.sys
magicbackupmonitor.sysmagicprotect.sysmajoradvapi.sysmarspy.sysmaxcryptmon.sys
maxproc64.sysmaxprotector.sysmbae64.sysmbam.sysmbamchameleon.sys
mbamshuriken.sysmbamswissarmy.sysmbamwatchdog.sysmblmon.sysmcfilemon32.sys
mcfilemon64.sysmcstrg.sysmearwfltdriver.sysmessage.sysmfdriver.sys
mfeaack.sysmfeaskm.sysmfeavfk.sysmfeclnrk.sysmfeelamk.sys
mfefirek.sysmfehidk.sysmfencbdc.sysmfencfilter.sysmfencoas.sys
mfencrk.sysmfeplk.sysmfewfpk.sysminiicpt.sysminispy.sys
minitrc.sysmlsaff.sysmmpsy32.sysmmpsy64.sysmonsterk.sys
mozycorpfilter.sysmozyenterprisefilter.sysmozyentfilter.sysmozyhomefilter.sysmozynextfilter.sys
mozyoemfilter.sysmozyprofilter.sysmpfilter.sysmpkernel.sysmpksldrv.sys
mpxmon.sysmracdrv.sysmrxgoogle.sysmscan-rt.sysmsiodrv4.sys
msixpackagingtoolmonitor.sysmsnfsflt.sysmspy.sysmssecflt.sysmtsvcdf.sys
mumdi.sysmwac.sysmwatcher.sysmwfsmfltr.sysmydlpmf.sys
namechanger.sysnanoavmf.sysnaswsp.sysndgdmk.sysneokerbyfilter
netaccctrl.sysnetaccctrl64.sysnetguard.sysnetpeeker.sysngscan.sys
nlcbhelpi64.sysnlcbhelpx64.sysnlcbhelpx86.sysnlxff.sysnmlhssrv01.sys
nmpfilter.sysnntinfo.sysnovashield.sysnowonmf.sysnpetw.sys
nprosec.sysnpxgd.sysnpxgd64.sysnravwka.sysnrcomgrdka.sys
nrcomgrdki.sysnregsec.sysnrpmonka.sysnrpmonki.sysnsminflt.sys
nsminflt64.sysntest.sysntfsf.sysntguard.sysntps_fa.sys
nullfilter.sysnvcmflt.sysnvmon.sysnwedriver.sysnxfsmon.sys
nxrmflt.sysoadevice.sysoavfm.sysoczminifilter.sysodfsfilter.sys
odfsfimfilter.sysodfstokenfilter.sysoffsm.sysomfltlh.sysosiris.sys
ospfile_mini.sysospmon.sysparity.syspassthrough.syspath8flt.sys
pavdrv.syspcpifd.syspctcore.syspctcore64.syspdgenfam.sys
pecfilter.sysperfectworldanticheatsys.syspervac.syspfkrnl.syspfracdrv.sys
pgpfs.syspgpwdefs.sysphantomd.sysphdcbtdrv.syspkgfilter.sys
pkticpt.sysplgfltr.sysplpoffdrv.syspointguardvista64f.syspointguardvistaf.sys
pointguardvistar32.syspointguardvistar64.sysprocmon11.sysproggerdriver.syspsacfileaccessfilter.sys
pscff.syspsgdflt.syspsgfoctrl.syspsinfile.syspsinproc.sys
psisolator.syspwipf6.syspwprotect.syspzdrvxp.sysqdocumentref.sys
qfapflt.sysqfilter.sysqfimdvr.sysqfmon.sysqminspec.sys
qmon.sysqqprotect.sysqqprotectx64.sysqqsysmon.sysqqsysmonx64.sys
qutmdrv.sysranpodfs.sysransomdefensexxx.sysransomdetect.sysreaqtor.sys
redlight.sysregguard.sysreghook.sysregmonex.sysrepdrv.sys
repmon.sysrevefltmgr.sysreveprocprotection.sysrevonetdriver.sysrflog.sys
rgnt.sysrmdiskmon.sysrmphvmonitor.sysrpwatcher.sysrrmon32.sys
rrmon64.sysrsfdrv.sysrsflt.sysrspcrtw.sysrsrtw.sys
rswctrl.sysrswmon.sysrtologon.sysrtw.sysruaff.sys
rubrikfileaudit.sysruidiskfs.sysruieye.sysruifileaccess.sysruimachine.sys
ruiminispy.sysrvsavd.sysrvsmon.sysrw7fsflt.sysrwchangedrv.sys
ryfilter.sysryguard.syssafe-agent.syssafsfilter.syssagntflt.sys
sahara.syssakfile.syssakmfile.syssamflt.syssamsungrapidfsfltr.sys
sanddriver.syssanta.syssascan.syssavant.syssavonaccess.sys
scaegis.sysscauthfsflt.sysscauthiodrv.sysscensemon.sysscfltr.sys
scifsflt.syssciptflt.syssconnect.sysscred.syssdactmon.sys
sddrvldr.syssdvfilter.sysse46filter.syssecdodriver.syssecone_filemon10.sys
secone_proc10.syssecone_reg10.syssecone_usb.syssecrmm.syssecufile.sys
secure_os.syssecure_os_mf.syssecurofsd_x64.syssefo.syssegf.sys
segiraflt.syssegmd.syssegmp.syssentinelmonitor.sysserdr.sys
serfs.syssfac.syssfavflt.syssfdfilter.syssfpmonitor.sys
sgresflt.sysshdlpmedia.sysshdlpsf.syssheedantivirusfilterdriver.syssheedselfprotection.sys
shldflt.syssi32_file.syssi64_file.syssieflt.syssimrep.sys
sisipsfilefiltersk.sysskyamdrv.sysskyrgdrv.sysskywpdrv.sys
slb_guard.syssld.syssmbresilfilter.syssmdrvnt.syssndacs.sys
snexequota.syssnilog.syssnimg.syssnscore.syssnsrflt.sys
sodatpfl.syssoftfilterxxx.syssoidriver.syssolitkm.syssonar.sys
sophosdt2.syssophosed.syssophosntplwf.syssophossupport.sysspbbcdrv.sys
spellmon.sysspider3g.sysspiderg3.sysspiminifilter.sysspotlight.sys
sprtdrv.syssqlsafefilterdriver.syssrminifilterdrv.syssrtsp.syssrtsp64.sys
srtspit.sysssfmonm.sysssrfsf.sysssvhook.sysstcvsm.sys
stegoprotect.sysstest.sysstflt.sysstkrnl64.sysstoragedrv.sys
strapvista.sysstrapvista64.syssvcbt.sysswcommfltr.sysswfsfltr.sys
swfsfltrv2.sysswin.syssymafr.syssymefa.syssymefa64.sys
symefasi.syssymevent.syssymevent64x86.syssymevnt.syssymevnt32.sys
symhsm.syssymrg.syssysdiag.syssysmon.syssysmondrv.sys
sysplant.sysszardrv.sysszdfmdrv.sysszdfmdrv_usb.sysszedrdrv.sys
szpcmdrv.systaniumrecorderdrv.systaobserveflt.systbfsfilt.systbmninifilter.sys
tbrdrv.systdevflt.systedrdrv.systenrsafe2.systesmon.sys
tesxnginx.systesxporter.systffregnt.systfsflt.systgfsmf.sys
thetta.systhfilter.systhreatstackfim.systkdac2k.systkdacxp.sys
tkdacxp64.systkfsavxp.systkfsavxp64.systkfsft.systkfsft64.sys
tkpcftcb.systkpcftcb64.systkpl2k.systkpl2k64.systksp2k.sys
tkspxp.systkspxp64.systmactmon.systmcomm.systmesflt.sys
tmevtmgr.systmeyes.systmfsdrv2.systmkmsnsr.systmnciesc.sys
tmpreflt.systmumh.systmums.systmusa.systmxpflt.sys
topdogfsfilt.systrace.systrfsfilter.systritiumfltr.systrpmnflt.sys
trufos.systrustededgeffd.systsifilemon.systss.syststfilter.sys
tstfsredir.syststregredir.systsyscare.systvdriver.systvfiltr.sys
tvmfltr.systvptfile.systvspfltr.systwbdcfilter.systxfilefilter.sys
txregmon.sysuamflt.sysucafltdriver.sysufdfilter.sysuncheater.sys
upguardrealtime.sysusbl_ifsfltr.sysusbpdh.sysusbtest.sysuvmcifsf.sys
uwfreg.sysuwfs.sysv3flt2k.sysv3flu2k.sysv3ift2k.sys
v3iftmnt.sysv3mifint.sysvarpffmon.sysvast.sysvcdriv.sys
vchle.sysvcmfilter.sysvcreg.sysveeamfct.sysvfdrv.sys
vfilefilter.sysvfpd.sysvfsenc.sysvhddelta.sysvhdtrack.sys
vidderfs.sysvintmfs.sysvirtfile.sysvirtualagent.sysvk_fsf.sys
vlflt.sysvmwvvpfsd.sysvollock.sysvpdrvnt.sysvradfil2.sys
vraptdef.sysvraptflt.sysvrarnflt.sysvrbbdflt.sysvrexpdrv.sys
vrfsftm.sysvrfsftmx.sysvrnsfilter.sysvrsdam.sysvrsdcore.sys
vrsdetri.sysvrsdetrix.sysvrsdfmx.sysvrvbrfsfilter.sysvsepflt.sys
vsscanner.sysvtsysflt.sysvxfsrep.syswats_se.syswbfilter.sys
wcsdriver.syswdcfilter.syswdfilter.syswdocsafe.syswfp_mrt.sys
wgfile.syswhiteshield.syswindbdrv.syswindd.syswinfladrv.sys
winflahdrv.syswinfldrv.syswinfpdrv.syswinload.syswinteonminifilter.sys
wiper.syswlminisecmod.syswntgpdrv.syswraekernel.syswrcore.sys
wrcore.x64.syswrdwizfileprot.syswrdwizregprot.syswrdwizscanner.syswrdwizsecure64.sys
wrkrn.syswrpfv.syswsafefilter.syswscm.sysxcpl.sys
xendowflt.sysxfsgk.sysxhunter1.sysxhunter64.sysxiaobaifs.sys
xiaobaifsr.sysxkfsfd.sysxoiv8x64.sysxomfcbt8x64.sysyahoostorage.sys
yfsd.sysyfsd2.sysyfsdr.sysyfsrd.syszampit_ml.sys
zesfsmf.syszqfilter.syszsfprt.syszwasatom.syszwpxesvr.sys
zxfsfilt.syszyfm.syszzpensys.sys  

Further reading

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