By: Joshua Platt and Jason Reaves

PrivateLoader[1,2,3,4] continues to function as an effective loading service, recently leveraging the use of SmokeLoader for their loads.

A recent sample of their SmokeLoader can be seen here(b01195c3e828d9a79c958e4c810a363d804d51996337db89a5d248096846b27a), the C2 domains for the sample are a hallmark for PrivateLoader:

host-file-host6.com
host-host-file8.com

These domains are simply proxies but behind them sits a massive operation performing millions of loads for various customers. Recently a new customer has started leveraging this service which caught our attention, in the aforementioned hash of SmokeLoader you can see all the tasks being ran:

From the DNS resolutions we can see SmokeLoader checking in along with quite a lot of other activity, some of them are related to tasks for the bot to load but the domain ‘deficulintersun[.]com’ is the C2 for an IcedID loader. Luckily Zenbox on VirusTotal left us with a PCAP so we can decrypt the SmokeLoader traffic and hopefully recover the tasks.

SmokeLoader C2 Traffic

xe4x078F1CEBFF99E357584119ACFBC1B392A2383170A8x00DESKTOP-B0T93D6x00pub3x00

So the group is pub3 and the version of the bot is 0x7e4 or 2020. The recovered tasks are as follows:

Location: http://rgyui.top/dl/buildz.exe
Location: https://dl.uploadgram.me/62e817d1aff5ah?dl
Location: https://allejee.com/bulking.exe
Location: http://194.87.31.137/7loader_exe_64.exe
Location: http://2.58.28.60/csflow.exe

SmokeLoader Tasks

The file I got from buildz.exe shows to be Djvu Ransomware, the more interesting part here is that the ransomware sample was crypted with the same crypter used for the SmokeLoader sample. Coupled with the fact that IcedID has been seen leading to ransomware itself, potentially a conflict of interest going on here between the service provider and their customers or competing customers?

Decoded Djvu strings:

http://acacaca.org/test1/get.php 2http://rgyui.top/dl/build2.exe$run http://acacaca.org/files/1/build3.exe$run 3Select Dec... 4_readme.txt 5ATTENTION! 6Don't worry, you can return all your files! 7All your files like pictures, databases, documents and other important are encrypted with s 8trongest encryption and unique key. 9The only method of recovering files is to purchase decrypt tool and unique key for you. 10This software will decry 11pt all your encrypted files. 12What guarantees you have? 13You can send one of your encrypted file from your PC and we decrypt it for free. 14But we can 15decrypt only 1 file for free. File must not contain valuable information. 16You can get and look video overview decrypt tool: 17https://we.tl/t-QsoSRIeA 18Price of private key and decrypt software is $980. 19Discount 50% available if you contact us first 72 hours, that's price for you is $490. 20Please 21 note that you'll never restore your data without payment. 22Check your e-mail "Spam" or "Junk" folder if you don't get answer more than 6 hours. 23To get this software you need write on our e-mail: 24support@bestyourmail.ch 25Reserve e-mail address to contact us: 26datarestorehelp@airmail.cc 27ur personal ID: 280530Jhyjd 29.vvew 30/acacaca.org/test1/get.php 31/acacaca.org/test1/get.php 32ntuser.dat|ntuser.dat.LOG1|ntuser.dat.LOG2|ntuser.pol|.sys|.ini|.DLL|.dll|.blf|.bat|.lnk|.regtrans-ms|C:SystemID|C:UsersDefault User|C:UsersPub 33lic|C:UsersAll Users|C:UsersDefault|C:Documents and Settings|C:ProgramData|C:Recovery|C:System Volume Information|C:Users%username%A 34ppDataRoaming|C:Users%username%AppDataLocal|C:Windows|C:PerfLogs|C:ProgramDataMicrosoft|C:ProgramDataPackage Cache|C:UsersPublic|C 35:$Recycle.Bin|C:$WINDOWS.~BT|C:dell|C:Intel|C:MSOCache|C:Program Files|C:Program Files (x86)|C:Games|C:Windows.old|D:Users%usernam 36e%AppDataRoaming|D:Users%username%AppDataLocal|D:Windows|D:PerfLogs|D:ProgramDataDesktop|D:ProgramDataMicrosoft|D:ProgramDataPacka 37ge Cache|D:UsersPublic|D:$Recycle.Bin|D:$WINDOWS.~BT|D:dell|D:Intel|D:MSOCache|D:Program Files|D:Program Files (x86)|D:Games|E:Us 38ers%username%AppDataRoaming|E:Users%username%AppDataLocal|E:Windows|E:PerfLogs|E:ProgramDataDesktop|E:ProgramDataMicrosoft|E:Progr 39amDataPackage Cache|E:UsersPublic|E:$Recycle.Bin|E:$WINDOWS.~BT|E:dell|E:Intel|E:MSOCache|E:Program Files|E:Program Files (x86)|E: 40Games|F:Users%username%AppDataRoaming|F:Users%username%AppDataLocal|F:Windows|F:PerfLogs|F:ProgramDataDesktop|F:ProgramDataMicroso 41ft|F:UsersPublic|F:$Recycle.Bin|F:$WINDOWS.~BT|F:dell|F:Intel 42-----BEGIN PUBLIC KEY-----nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwX6oUNb4mk19lyNBxK80nWDzdQgJ9XMg2LdYk3Hm0F0zP2rWDuKVpyAbosbOzGKbJOkVa/1Xby 43tFAm8RYfkB/nnfEgGh5OGcw/CcqqOL3R4Vpd7slLVXc56FLkTWEMSShzg1sNxgIiQm8VcaXOgUk8ntvWKcUIV9ujXmn5UBSy/ICDPveI3QCaxZod7kIBwZzszO/3CvNwAy3eejgJ6j8ie 44nmwJ9pjskzLjmq92yhDGUQygWfGw0tL1KtSiqUy2M7KNdmD4FX1aVeutZC9bggvn8nV4ksJChvMxI521ms58donyKjwBAbKXBfVRaXUV2k34bI0NQqhLz5OeGIRhn67oe+njwIDAQABn--- 45--END PUBLIC KEY----- 46ild2.exe$run http://acacaca.org/files/1/build3.exe$run 47rE5LpDv2ftYRXAo7bC18EpzfRMTHSGjgfyIMfZt1 48/acacaca.org/files/1/build3.exe$run

The file from uploadgram, 62e817d1aff5ah, turns out be RedLine stealer:

{'C2': '193.233.193.14:8163', 'BOTNET': 'LogsDiller Cloud (Sup: @mr_golds)'}

The file from allejee was down at the time we found it but we did find same name files from that server in VirusTotal:

03626471a65baf211f2110cd91e52b9e44524780e042a473cd09d864d9af20a0

Which has ITW URLs from the same server in July:

This file is a self extracting EXE signed by ‘Nir Sofer’, the extracted EXE inside of it ends up being a simple .NET based loader which will download and execute more .NET code, eventually this leads to Racoon Stealer V2[5].

The csflow.exe executable is an installer for CoinSurf which allows people to monetize their traffic usage.

Finally the 7loader_exe_64.exe file is an IcedID loader:

{'C2': 'deficulintersun.com', 'Campaign': 1514253643}

PrivateLoader is not new to having some bigger names leveraging it as previous research indicates it being leveraged by TrickBot, Qakbot, DanaBot and Dridex previously. The more pressing question is why these groups would leverage a system that is actively stealing data and dropping ransomware on top of their bots?

IOCs

SmokeBot tasks:

Network indicators:

rgyui.top
allejee.com
194.87.31.137
2.58.28.60
host-file-host6.com
host-host-file8.com
64.52.80.224 - Raccoon Stealer
deficulintersun.com - IcedID
acacaca.org - Djvu Ransomware
193.233.193.14:8163 - RedLine Stealer
2.58.28.60/install.txt
2.58.28.60/startup.txt

References

1: https://intel471.com/blog/privateloader-malware

2: https://medium.com/walmartglobaltech/privateloader-to-anubis-loader-55d066a2653e

3: https://www.zscaler.com/blogs/security-research/peeking-privateloader

4: https://tavares.re/blog/2022/06/06/hunting-privateloader-pay-per-install-service/

5: https://www.bleepingcomputer.com/news/security/raccoon-stealer-is-back-with-a-new-version-to-steal-your-passwords/