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PYSA Ransomware Gang adds Linux Support

Key Take Aways

  • The first Linux version of ChaChi, a Golang based DNS tunneling backdoor, was recently observed on VirusTotal.
  • The malware is configured to use domains associated with ransomware actors known as PYSA, aka Menipoza Ransomware Gang.
  • PYSA’s ChaChi infrastructure appears to have been largely dormant for the past several weeks, mostly parked and apparently no longer operational.
  • We assess with moderate confidence this sample represents the PYSA actor expanding into targeting Linux hosts with ChaChi backdoor.

Background

Ransomware is quickly expanding into Linux and Cloud networks as threat actors evolve their campaigns. For example, in recent weeks the BlackMatter ransomware gang, HelloKitty ransomware, and REvil ransomware were first observed expanding into Linux targeting through ESXi servers with ELF encryptors. Ransomware shifts to Linux targeting is an important trend to observe. Threat actors continue to evolve their campaigns by targeting Linux and cloud-centric networks.

Analysis

In August of 2021, Lacework Labs identified a Linux variant (MD5: 14abd57e8eb06191f12c0d84f9c1470b) of ChaChi. ChaChi refers to a customized variant of an open-source Golang based RAT that leverages DNS tunneling for C2 communication. The specimen was configured with domains that were reported by Palo Alto Networks in July:

  • sbvjhs.xyz
  • sbvjhs.club
  • firefox-search.xyz

While the specimen was recently observed, it was uploaded to VirusTotal June 14th 2021, and only had 1/61 AV detections at the time. Following our tweet in late August, and as of this writing, it’s currently at a 20/61 detection rate.

Chachi AV detection over time
Figure 1. AV detection over time

 

The Linux variant shares characteristics with its Windows counterpart, most notable being core functionality, the large file size (8MB +) and the use of Golang obfuscator Gobfuscate. A distinguishing characteristic of the Linux version was the presence of debug output containing datetime data.

Chachi Debug Output
Figure 2. Debug Output

 

ChaChi leverages custom nameservers that double as C2s to support the DNS tunneling protocol. As such the C2 hosts can be identified with passive DNS analysis of the name server domains. Analysis shows that the majority of ChaChi infrastructure has been parked or offline since 23-24 June 2021. The two exceptions to this appear to be domains ns1.ccenter.tech and ns2.spm.best.

C2 Whois and nameservers example
Figure 3. C2 Whois and nameservers example

 

At the time of this blog, two domains from the Linux variant (sbvjhs.xyz and sbvjhs.club) resolved to Amazon IP address 99.83.154.118. This IP is an AWS Global accelerator host and has several AV detections on VirusTotal, however, our analysis indicates this is most likely used by Namecheap for domain parking purposes and should not be used as a ChaChi IOC. The following table lists known Chachi nameservers along with their resolutions. Several domains have been parked on either Amazon or Namecheap but these were filtered out.

HOSTNAME

IP_ADDR

ASN

COUNTRY

FIRST_SEEN

LAST_SEEN

ns1.englishdialoge.xyz

160.20.147.184

30823:”combahton GmbH”

Germany

Thu, 26 Nov 2020 23:27:18 -0800

Thu, 24 Jun 2021 09:22:03 -0700

ns2.englishdialoge.xyz

160.20.147.184

30823:”combahton GmbH”

Germany

Thu, 26 Nov 2020 23:27:18 -0800

Thu, 24 Jun 2021 09:22:03 -0700

ns1.englishdict.xyz

172.96.189.167

20068:”HAWKHOST”

Canada

Thu, 05 Nov 2020 03:39:33 -0800

Thu, 24 Jun 2021 06:26:43 -0700

ns2.englishdict.xyz

172.96.189.167

20068:”HAWKHOST”

Canada

Thu, 05 Nov 2020 03:39:33 -0800

Thu, 24 Jun 2021 06:26:43 -0700

ns1.english-breakfast.xyz

172.96.189.22

20068:”HAWKHOST”

Canada

Tue, 15 Dec 2020 15:45:14 -0800

Thu, 24 Jun 2021 13:38:42 -0700

ns1.english-breakfast.xyz

172.96.189.22

20068:”HAWKHOST”

Canada

Tue, 15 Dec 2020 15:45:14 -0800

Thu, 24 Jun 2021 13:38:42 -0700

ns1.pump-online.xyz

172.96.189.246

20068:”HAWKHOST”

Canada

Tue, 15 Dec 2020 15:45:55 -0800

Thu, 24 Jun 2021 05:00:38 -0700

ns2.english-breakfast.xyz

172.96.189.246

20068:”HAWKHOST”

Canada

Tue, 15 Dec 2020 15:45:14 -0800

Thu, 24 Jun 2021 13:38:42 -0700

ns2.english-breakfast.xyz

172.96.189.246

20068:”HAWKHOST”

Canada

Tue, 15 Dec 2020 15:45:14 -0800

Thu, 24 Jun 2021 13:38:42 -0700

ns2.pump-online.xyz

172.96.189.246

20068:”HAWKHOST”

Canada

Tue, 15 Dec 2020 15:45:55 -0800

Thu, 24 Jun 2021 05:00:38 -0700

ns1.blitzz.best

185.185.27.3

201206:”Droptop GmbH”

Germany

Sat, 06 Jun 2020 01:29:35 -0700

Wed, 02 Jun 2021 11:14:52 -0700

ns2.blitzz.best

185.185.27.3

201206:”Droptop GmbH”

Germany

Sat, 06 Jun 2020 01:29:35 -0700

Wed, 02 Jun 2021 11:14:52 -0700

ns1.firefox-search.xyz

185.186.245.85

40824:”WZCOM”

United States

Mon, 07 Sep 2020 15:35:41 -0700

Wed, 23 Jun 2021 07:31:39 -0700

ns2.firefox-search.xyz

185.186.245.85

40824:”WZCOM”

United States

Mon, 07 Sep 2020 15:35:41 -0700

Wed, 23 Jun 2021 07:31:39 -0700

ns1.reportservicefuture.website

185.193.38.60

57878:”Prager Connect GmbH”

France

Sat, 09 May 2020 11:04:41 -0700

Sun, 02 May 2021 08:04:13 -0700

ns2.reportservicefuture.website

185.193.38.60

57878:”Prager Connect GmbH”

France

Sat, 09 May 2020 11:04:41 -0700

Sun, 02 May 2021 08:04:13 -0700

ns1.wiki-text.xyz

193.239.84.205

9009:”M247 Ltd”

United Kingdom

Thu, 03 Sep 2020 15:58:08 -0700

Wed, 23 Jun 2021 08:18:42 -0700

ns2.wiki-text.xyz

193.239.84.205

9009:”M247 Ltd”

United Kingdom

Thu, 03 Sep 2020 15:58:08 -0700

Wed, 23 Jun 2021 08:18:42 -0700

ns1.visual-translator.xyz

193.239.85.55

9009:”M247 Ltd”

Romania

Thu, 03 Sep 2020 14:35:02 -0700

Wed, 23 Jun 2021 08:18:41 -0700

ns2.visual-translator.xyz

193.239.85.55

9009:”M247 Ltd”

Romania

Thu, 03 Sep 2020 14:35:02 -0700

Wed, 23 Jun 2021 08:18:41 -0700

ns1.sbvjhs.xyz

194.187.249.102

9009:”M247 Ltd”

France

Sat, 01 Aug 2020 21:29:06 -0700

Wed, 23 Jun 2021 07:08:08 -0700

ns2.sbvjhs.xyz

194.187.249.102

9009:”M247 Ltd”

France

Sat, 01 Aug 2020 21:29:06 -0700

Wed, 23 Jun 2021 07:08:08 -0700

ns1.statistics-update.xyz

194.5.249.18

64398:”Nxtservers Srl”

Romania

Fri, 31 Jul 2020 09:23:54 -0700

Wed, 23 Jun 2021 06:56:20 -0700

ns2.statistics-update.xyz

194.5.249.18

64398:”Nxtservers Srl”

Romania

Fri, 31 Jul 2020 09:23:54 -0700

Wed, 23 Jun 2021 06:56:20 -0700

ns1.accounting-consult.xyz

194.5.249.180

64398:”Nxtservers Srl”

Romania

Sun, 02 Aug 2020 06:27:13 -0700

Wed, 23 Jun 2021 07:37:33 -0700

ns2.accounting-consult.xyz

194.5.249.180

64398:”Nxtservers Srl”

Romania

Sun, 02 Aug 2020 06:27:13 -0700

Wed, 23 Jun 2021 07:37:33 -0700

ns1.ntservicepack.com

194.5.250.216

64398:”Nxtservers Srl”

Romania

Wed, 29 Apr 2020 10:19:42 -0700

Tue, 24 Nov 2020 00:58:02 -0800

ns2.ntservicepack.com

194.5.250.216

64398:”Nxtservers Srl”

Romania

Wed, 29 Apr 2020 10:19:42 -0700

Tue, 24 Nov 2020 00:58:02 -0800

ns1.starhouse.xyz

198.252.100.37

20068:”HAWKHOST”

United States

Thu, 26 Nov 2020 21:55:56 -0800

Thu, 24 Jun 2021 14:24:10 -0700

ns2.starhouse.xyz

198.252.100.37

20068:”HAWKHOST”

United States

Thu, 26 Nov 2020 21:55:56 -0800

Thu, 24 Jun 2021 14:24:10 -0700

ns1.ccenter.tech

23.83.133.136

19148:”LEASEWEB-USA-PHX-11”

United States

Wed, 24 Mar 2021 12:30:02 -0700

Tue, 31 Aug 2021 04:10:51 -0700

ns2.ccenter.tech

23.83.133.136

19148:”LEASEWEB-USA-PHX-11”

United States

Wed, 24 Mar 2021 12:30:02 -0700

Tue, 31 Aug 2021 04:10:51 -0700

ns1.transnet.wiki

45.147.228.49

30823:”combahton GmbH”

Germany

Wed, 24 Mar 2021 12:30:03 -0700

Wed, 23 Jun 2021 08:13:07 -0700

ns2.transnet.wiki

45.147.228.49

30823:”combahton GmbH”

Germany

Wed, 24 Mar 2021 12:30:03 -0700

Wed, 23 Jun 2021 08:13:07 -0700

ns1.productoccup.tech

45.147.229.29

30823:”combahton GmbH”

Germany

Tue, 23 Mar 2021 03:17:32 -0700

Thu, 24 Jun 2021 07:16:58 -0700

ns2.productoccup.tech

45.147.229.29

30823:”combahton GmbH”

Germany

Tue, 23 Mar 2021 03:17:32 -0700

Thu, 24 Jun 2021 07:16:58 -0700

ns2.spm.best

72.52.178.23

32244:”LIQUIDWEB”

United States

Fri, 23 Jul 2021 04:32:25 -0700

Tue, 31 Aug 2021 06:03:43 -0700

ns1.sbvjhs.club

89.38.225.208

9009:”M247 Ltd”

Singapore

Sun, 02 Aug 2020 05:45:47 -0700

Wed, 23 Jun 2021 11:33:13 -0700

ns2.sbvjhs.club

89.38.225.208

9009:”M247 Ltd”

Singapore

Sun, 02 Aug 2020 05:45:47 -0700

Wed, 23 Jun 2021 11:33:13 -0700

ns1.serchtext.xyz

89.41.26.173

9009:”M247 Ltd”

United States

Mon, 02 Nov 2020 13:30:18 -0800

Thu, 24 Jun 2021 06:26:39 -0700

ns2.serchtext.xyz

89.41.26.173

9009:”M247 Ltd”

United States

Mon, 02 Nov 2020 13:30:18 -0800

Thu, 24 Jun 2021 06:26:39 -0700

 

Conclusion

Many actors target multiple architectures to increase their footprint, so this may be the motive here and could represent an evolution in PYSA operations. It is currently unclear if the Linux variant was used in operations, however it was observed prior to the associated infrastructure going offline. The observed debug output however may indicate the specimen is still in the testing phase.

Ransomware is hugely lucrative and actors are continuously looking for any edge that will increase their profits. While ransomware activity involving Linux Servers and cloud infrastructure remains rare, it still poses a real threat to business operations and customer data. Indicators for this activity are available on the Lacework Labs’s Github. If you found this blog useful then please share and follow us on LinkedIn and Twitter!

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