07/22/2024 | Press release | Distributed by Public on 07/23/2024 07:14
Affected Platforms: Microsoft Windows
Impacted Users: Microsoft Windows
Impact: The stolen information can be used for future attack
Severity Level: High
CVE-2024-21412 is a security bypass vulnerability in Microsoft Windows SmartScreen that arises from an error in handling maliciously crafted files. A remote attacker can exploit this flaw to bypass the SmartScreen security warning dialog and deliver malicious files. Over the past year, several attackers, including Water Hydra, Lumma Stealer, and Meduza Stealer, have exploited this vulnerability.
FortiGuard Labs has observed a stealer campaign spreading multiple files that exploit CVE-2024-21412 to download malicious executable files. Initially, attackers lure victims into clicking a crafted link to a URL file designed to download an LNK file. The LNK file then downloads an executable file containing an HTA script. Once executed, the script decodes and decrypts PowerShell code to retrieve the final URLs, decoy PDF files, and a malicious shell code injector. These files aim to inject the final stealer into legitimate processes, initiating malicious activities and sending the stolen data back to a C2 server.
The threat actors have designed different injectors to evade detection and use various PDF files to target specific regions, including North America, Spain, and Thailand. This article elaborates on how these files are constructed and how the injector works.
Initial Access
To start, the attacker constructs a malicious link to a remote server to search for a URL file with the following content:
The target LNK file employs the "forfiles" command to invoke PowerShell, then executes "mshta" to fetch an execution file from the remote server "hxxps://21centuryart.com."
During our investigation, we collected several LNK files that all download similar executables containing an HTA script embedded within the overlay. This HTA script has set WINDOWSTATE="minimize" and SHOWTASKBAR="no." It plays a crucial role in the infection chain by executing additional malicious code and seamlessly facilitating the next stages of the attack.
After decoding and decrypting the script, a PowerShell code downloads two files to the "%AppData%" folder. The first is a decoy PDF, a clean file that extracts the victim's attention from malicious activity, and the other is an execution file that injects shell code for the next stage.
Shell Code Injector
In this attack chain, we identified two types of injectors. The first leverages an image file to obtain a shell code. As of mid-July, it had low detection rates on VirusTotal.
After anti-debugging checking, it starts downloading a JPG file from the Imghippo website, "hxxps://i.imghippo[.]com/files/0hVAM1719847927[.]png." It then uses the Windows API "GdipBitmapGetPixel" to access the pixels and decode the bytes to get the shell code.
It then calls "dword ptr ss:[ebp-F4]" to the entry point of the shell code. The shell code first obtains all the APIs from a CRC32 hash, creates a folder, and drops files in "%TEMP%." We can tell that these dropped files are HijackLoader based on the typical bytes "\x49\x44\x 41\x54\xC6\xA5\x79\xEA" found in the encrypted data.
The other injector is more straightforward. It decrypts its code from the data section and uses a series of Windows API functions-NtCreateSection, NtMapViewOfSection, NtUnmapViewOfSection, NtMapViewOfSection again, and NtProtectVirtualMemory-to perform shell code injection.
Final Stealers
This attack uses Meduza Stealer version 2.9 and the panel found at hxxp://5[.]42[.]107[.]78/auth/login.
We also identified an ACR stealer loaded from HijackLoader. This ACR stealer hides its C2 with a dead drop resolver (DDR) technique on the Steam community website, hxxps://steamcommunity[.]com/profiles/76561199679420718.
We also found the C2 for other ACR Stealers on Steam by searching for the specific string, "t6t".
After retrieving the C2 hostname, the ACR stealer appends specific strings to construct a complete URL, "hxxps://pcvcf[.]xyz/ujs/a4347708-adfb-411c-8f57-c2c166fcbe1d". This URL then fetches the encoded configuration from the remote server. The configuration data typically contains crucial information, such as target specifics and operational parameters for the stealer. By decoding the C2 from Steam, the stealer can adapt legitimate web services to maintain communications with its C2 server.
Except for local text files in paths "Documents" and "Recent, " ACR Stealer has the following target applications:
nphplpgoakhhjchkkhmiggakijnkhfnd |
apbldaphppcdfbdnnogdikheafliigcf |
fldfpgipfncgndfolcbkdeeknbbbnhcc |
ckdjpkejmlgmanmmdfeimelghmdfeobe |
omaabbefbmiijedngplfjmnooppbclkk |
iodngkohgeogpicpibpnaofoeifknfdo |
afbcbjpbpfadlkmhmclhkeeodmamcflc |
hnefghmjgbmpkjjfhefnenfnejdjneog |
lodccjjbdhfakaekdiahmedfbieldgik |
fpcamiejgfmmhnhbcafmnefbijblinff |
hcflpincpppdclinealmandijcmnkbgn |
egdddjbjlcjckiejbbaneobkpgnmpknp |
bcopgchhojmggmffilplmbdicgaihlkp |
nihlebdlccjjdejgocpogfpheakkpodb |
fhmfendgdocmcbmfikdcogofphimnkno |
ilbibkgkmlkhgnpgflcjdfefbkpehoom |
kpfopkelmapcoipemfendmdcghnegimn |
oiaanamcepbccmdfckijjolhlkfocbgj |
fhbohimaelbohpjbbldcngcnapndodjp |
ldpmmllpgnfdjkmhcficcifgoeopnodc |
cnmamaachppnkjgnildpdmkaakejnhae |
mbcafoimmibpjgdjboacfhkijdkmjocd |
nlbmnnijcnlegkjjpcfjclmcfggfefdm |
jbdpelninpfbopdfbppfopcmoepikkgk |
amkmjjmmflddogmhpjloimipbofnfjih |
onapnnfmpjmbmdcipllnjmjdjfonfjdm |
cphhlgmgameodnhkjdmkpanlelnlohao |
cfdldlejlcgbgollnbonjgladpgeogab |
kncchdigobghenbbaddojjnnaogfppfj |
ablbagjepecncofimgjmdpnhnfjiecfm |
jojhfeoedkpkglbfimdfabpdfjaoolaf |
fdfigkbdjmhpdgffnbdbicdmimfikfig |
ffnbelfdoeiohenkjibnmadjiehjhajb |
njojblnpemjkgkchnpbfllpofaphbokk |
pdgbckgdncnhihllonhnjbdoighgpimk |
hjagdglgahihloifacmhaigjnkobnnih |
ookjlbkiijinhpmnjffcofjonbfbgaoc |
pnlccmojcmeohlpggmfnbbiapkmbliob |
mnfifefkajgofkcjkemidiaecocnkjeh |
ljfpcifpgbbchoddpjefaipoiigpdmag |
flpiciilemghbmfalicajoolhkkenfel |
bhghoamapcdpbohphigoooaddinpkbai |
jfdlamikmbghhapbgfoogdffldioobgl |
gaedmjdfmmahhbjefcbgaolhhanlaolb |
nkbihfbeogaeaoehlefnkodbefgpgknn |
imloifkgjagghnncjkhggdhalmcnfklk |
aiifbnbfobpmeekipheeijimdpnlpgpp |
oeljdldpnmdbchonielidgobddffflal |
aeachknmefphepccionboohckonoeemg |
ilgcnhelpchnceeipipijaljkblbcobl |
hpglfhgfnhbgpjdenjgmdgoeiappafln |
nngceckbapebfimnlniiiahkandclblb |
nknhiehlklippafakaeklbeglecifhad |
oboonakemofpalcgghocfoadofidjkkk |
dmkamcknogkgcdfhhbddcghachkejeap |
fdjamakpfbbddfjaooikfcpapjohcfmg |
jnmbobjmhlngoefaiojfljckilhhlhcj |
fooolghllnmhmmndgjiamiiodkpenpbb |
klnaejjgbibmhlephnhpmaofohgkpgkd |
bfogiafebfohielmmehodmfbbebbbpei |
ibnejdfjmmkpcnlpebklmnkoeoihofec |
lfochlioelphaglamdcakfjemolpichk |
ejbalbakoplchlghecdalmeeeajnimhm |
hdokiejnpimakedhajhdlcegeplioahd |
kjmoohlgokccodicjjfebfomlbljgfhk |
naepdomgkenhinolocfifgehidddafch |
fnjhmkhhmkbjkkabndcnnogagogbneec |
bmikpgodpkclnkgmnpphehdgcimmided |
nhnkbkgjikgcigadomkphalanndcapjk |
nofkfblpeailgignhkbnapbephdnmbmn |
hnfanknocfeofbddgcijnmhnfnkdnaad |
jhfjfclepacoldmjmkmdlmganfaalklb |
cihmoadaighcejopammfbmddcmdekcje |
chgfefjpcobfbnpmiokfjjaglahmnded |
bfnaelmomeimhlpmgjnjophhpkkoljpa |
igkpcodhieompeloncfnbekccinhapdb |
djclckkglechooblngghdinmeemkbgci |
cfhdojbkjhnklbpkdaibdccddilifddb |
jiidiaalihmmhddjgbnbgdfflelocpak |
kmmkllgcgpldbblpnhghdojehhfafhro |
lgmpcpglpngdoalbgeoldeajfclnhafa |
ibegklajigjlbljkhfpenpfoadebkokl |
egjidjbpglichdcondbcbdnbeeppgdph |
ijpdbdidkomoophdnnnfoancpbbmpfcn |
flhbololhdbnkpnnocoifnopcapiekdi |
llalnijpibhkmpdamakhgmcagghgmjab |
kkhmbjifakpikpapdiaepgkdephjgnma |
mjdmgoiobnbombmnbbdllfncjcmopfnc |
ekkhlihjnlmjenikbgmhgjkknoelfped |
dlcobpjiigpikoobohmabehhmhfoodbb |
jngbikilcgcnfdbmnmnmnleeomffciml |
jnlgamecbpmbajjfhmmmlhejkemejdma |
hcjginnbdlkdnnahogchmeidnmfckjom |
kbdcddcmgoplfockflacnnefaehaiocb |
ogphgbfmhodmnmpnaadpbdadldbnmjji |
kgdijkcfiglijhaglibaidbipiejjfdp |
hhmkpbimapjpajpicehcnmhdgagpfmjc |
epapihdplajcdnnkdeiahlgigofloibg |
ojhpaddibjnpiefjkbhkfiaedepjheca |
mgffkfbidihjpoaomajlbgchddlicgpn |
fmhjnpmdlhokfidldlglfhkkfhjdmhgl |
ebfidpplhabeedpnhjnobghokpiioolj |
gjhohodkpobnogbepojmopnaninookhj |
dngmlblcodfobpdpecaadgfbcggfjfnm |
hmglflngjlhgibbmcedpdabjmcmboamo |
ldinpeekobnhjjdofggfgjlcehhmanlj |
eklfjjkfpbnioclagjlmklgkcfmgmbpg |
mdjmfdffdcmnoblignmgpommbefadffd |
jbkfoedolllekgbhcbcoahefnbanhhlh |
aflkmfhebedbjioipglgcbcmnbpgliof |
mcohilncbfahbmgdjkbpemcciiolgcge |
dmjmllblpcbmniokccdoaiahcdajdjof |
jbdaocneiiinmjbjlgalhcelgbejmnid |
lnnnmfcpbkafcpgdilckhmhbkkbpkmid |
blnieiiffboillknjnepogjhkgnoapac |
odpnjmimokcmjgojhnhfcnalnegdjmdn |
cjelfplplebdjjenllpjcblmjkfcffne |
bopcbmipnjdcdfflfgjdgdjejmgpoaab |
fihkakfobkmkjojpchpfgcmhfjnmnfpi |
cpmkedoipcpimgecpmgpldfpohjplkpp |
kkpllkodjeloidieedojogacfhpaihoh |
khpkpbbcccdmmclmpigdgddabeilkdpd |
nanjmdknhkinifnkgdcggcfnhdaammmj |
mcbigmjiafegjnnogedioegffbooigli |
nkddgncdjgjfcddamfgcmfnlhccnimig |
fiikommddbeccaoicoejoniammnalkfa |
acmacodkjbdgmoleebolmdjonilkdbch |
heefohaffomkkkphnlpohglngmbcclhi |
phkbamefinggmakgklpkljjmgibohnba |
ocjdpmoallmgmjbbogfiiaofphbjgchh |
efbglgofoippbgcjepnhiblaibcnclgk |
hmeobnfnfcmdkdcmlblgagmfpfboieaf |
lpfcbjknijpeeillifnkikgncikgfhdo |
kfdniefadaanbjodldohaedphafoffoh |
ejjladinnckdgjemekebdpeokbikhfci |
kmhcihpebfmpgmihbkipmjlmmioameka |
opcgpfmipidbgpenhmajoajpbobppdil |
gafhhkghbfjjkeiendhlofajokpaflmk |
aholpfdialjgjfhomihkjbmgjidlcdno |
kglcipoddmbniebnibibkghfijekllbl |
onhogfjeacnfoofkfgppdlbmlmnplgbn |
iokeahhehimjnekafflcihljlcjccdbe |
mopnmbcafieddcagagdcbnhejhlodfdd |
idnnbdplmphpflfnlkomgpfbpcgelopg |
fijngjgcjhjmmpcmkeiomlglpeiijkld |
kmphdnilpmdejikjdnlbcnmnabepfgkh |
hifafgmccdpekplomjjkcfgodnhcellj |
cgeeodpfagjceefieflmdfphplkenlfk |
ijmpgkjfkbfhoebgogflfebnmejmfbm |
pdadjkfkgcafgbceimcpbkalnfnepbnk |
lkcjlnjfpbikmcmbachjpdbijejflpcm |
odbfpeeihdkbihmopkbjmoonfanlbfcl |
onofpnbbkehpmmoabgpcpmigafmmnjh |
fhilaheimglignddkjgofkcbgekhenbh |
dkdedlpgdmmkkfjabffeganieamfklkm |
aodkkagnadcbobfpggfnjeongemjbjca |
nlgbhdfgdhgbiamfdfmbikcdghidoadd |
dngmlblcodfobpdpecaadgfbcggfjfnm |
infeboajgfhgbjpjbeppbkgnabfdkdaf |
lpilbniiabackdjcionkobglmddfbcjo |
ppbibelpcjmhbdihakflkdcoccbgbkpo |
bhhhlbepdkbapadjdnnojkbgioiodbic |
klghhnkeealcohjjanjjdaeeggmfmlpl |
jnkelfanjkeadonecabehalmbgpfodjm |
enabgbdfcbaehmbigakijjabdpdnimlg |
jgaaimajipbpdogpdglhaphldakikgef |
mmmjbcfofconkannjonfmjjajpllddbg |
kppfdiipphfccemcignhifpjkapfbihd |
bifidjkcdpgfnlbcjpdkdcnbiooooblg |
loinekcabhlmhjjbocijdoimmejangoa |
nebnhfamliijlghikdgcigoebonmoibm |
anokgmphncpekkhclmingpimjmcooifb |
fcfcfllfndlomdhbehjjcoimbgofdncg |
cnncmdhjacpkmjmkcafchppbnpnhdmon |
ojggmchlghnjlapmfbnjholfjkiidbch |
mkpegjkblkkefacfnmkajcjmabijhclg |
Conclusion
This campaign primarily targets CVE-2024-21412 to spread LNK files for downloading execution files that embed HTA script code within their overlays. The HTA script runs silently, avoiding any pop-up windows, and clandestinely downloads two files: a decoy PDF and an execution file designed to inject shell code, setting the stage for the final stealers.
To mitigate such threats, organizations must educate their users about the dangers of downloading and running files from unverified sources. Continuous innovation by threat actors necessitates a robust and proactive cybersecurity strategy to protect against sophisticated attack vectors. Proactive measures, user awareness, and stringent security protocols are vital components in safeguarding an organization's digital assets.
Fortinet Protections
The malware described in this report is detected and blocked by FortiGuard Antivirus:
LNK/Agent.OQ!tr
LNK/Agent.BNE!tr
LNK/Agent.ACX!tr
W32/Agent.DAT!tr
W64/Agent.EDE6!tr
W32/Agent.AAN!tr
W64/Agent.A8D2!tr
FortiGate, FortiMail, FortiClient, and FortiEDR support the FortiGuard AntiVirus service. The FortiGuard AntiVirus engine is part of each of these solutions. As a result, customers who have these products with up-to-date protections are protected.
The FortiGuard Web Filtering Service blocks the C2 servers and downloads URLs.
FortiGuard Labs provides IPS signature against attacks exploiting CVE-2024-21412:
MS.Windows.SmartScreen.CVE-2024-21412.Security.Feature.Bypass
We also suggest that organizations go through Fortinet's free NSE training module: NSE 1 - Information Security Awareness. This module is designed to help end users learn how to identify and protect themselves from phishing attacks.
FortiGuard IP Reputation and Anti-Botnet Security Service proactively block these attacks by aggregating malicious source IP data from the Fortinet distributed network of threat sensors, CERTs, MITRE, cooperative competitors, and other global sources that collaborate to provide up-to-date threat intelligence about hostile sources.
If you believe this or any other cybersecurity threat has impacted your organization, please contact our Global FortiGuard Incident Response Team.
IOCs
IP Addresses
62[.]133[.]61[.]26
62[.]133[.]61[.]43
5[.]42[.]107[.]78
Hostnames
21centuryart[.]com
scratchedcards[.]com
proffyrobharborye[.]xyz
answerrsdo[.]shop
pcvcf[.]xyz
pcvvf[.]xyz
pdddk[.]xyz
pdddj[.]xyz
pddbj[.]xyz
pbpbj[.]xyz
pbdbj[.]xyz
ptdrf[.]xyz
pqdrf[.]xyz
Files
e15b200048fdddaedb24a84e99d6d7b950be020692c02b46902bf5af8fb50949
547b6e08b0142b4f8d024bac78eb1ff399198a8d8505ce365b352e181fc4a544
bd823f525c128149d70f633e524a06a0c5dc1ca14dd56ca7d2a8404e5a573078
982338768465b79cc8acd873a1be2793fccbaa4f28933bcdf56b1d8aa6919b47
bc6933a8fc324b907e6cf3ded3f76adc27a6ad2445b4f5db1723ac3ec86ed10d
59d2c2ca389ab1ba1fefa4a06b14ae18a8f5b70644158d5ec4fb7a7eac4c0a08
8568226767ac2748eccc7b9832fac33e8aa6bfdc03eafa6a34fb5d81e5992497
4043aa37b5ba577dd99f6ca35c644246094f4f579415652895e6750fb9823bd9
0604e7f0b4f7790053991c33359ad427c9bf74c62bec3e2d16984956d0fb9c19
8c6d355a987bb09307e0af6ac8c3373c1c4cbfbceeeb1159a96a75f19230ede6
de6960d51247844587a21cc0685276f966747e324eb444e6e975b0791556f34f
6c779e427b8d861896eacdeb812f9f388ebd43f587c84a243c7dab9ef65d151c
08c75c6a9582d49ea3fe780509b6f0c9371cfcd0be130bc561fae658b055a671
abc54ff9f6823359071d755b151233c08bc2ed1996148ac61cfb99c7e8392bfe
643dde3f461907a94f145b3cd8fe37dbad63aec85a4e5ed759fe843b9214a8d2