Executive Summary
On February 3, European hosting providers and computer emergency response teams (CERTs) began warning of a widespread ransomware campaign exploiting CVE-2021-21974, a VMWare ESXi vulnerability for which a patch has been available since February 2021.
Shortly after the warnings’ publication, SecurityScorecard developed an emergency informational signal to give customers visibility into potentially impacted servers.
The SecurityScorecard Threat Research, Intelligence, Knowledge, and Engagement (STRIKE) Team began an investigation into this new campaign in response to the advisories about it.
Our Attack Surface Intelligence (ASI) tool has revealed a population of servers that may be subject to this vulnerability, and our global network flow (netflow) analysis capability (available via professional services) has uncovered possible communication between target IP addresses and infrastructure involved in the exploitation of this vulnerability.
Background
Beginning on February 3, European hosting providers and computer emergency response teams (CERTs) began warning of a widespread ransomware campaign exploiting CVE-2021-21974, a VMWare ESXi vulnerability for which a patch has been available since February 2021. In their initial warning regarding the vulnerability, French cloud service provider OVH linked this activity to the Nevada ransomware group, but subsequently retracted this attribution. The cybersecurity community has instead taken to tracking the campaign as ESXiArgs, as the ransomware involved creates a file with a .args extension once it encrypts a file.
Especially in light of OVH’s retraction, it may bear noting that ESXiArgs is not the only ransomware campaign to target ESXi; Croatia’s CERT published a flowchart that specifically helps distinguish ESXiArgs activity from that of the aforementioned Nevada ransomware group, indicating that the Nevada group does indeed target ESXi services as well, but that this activity is distinct from ESXiArgs. Similarly, research circulated on February 5 noted that the Royal ransomware group had also begun targeting ESXi, and recent years also have also seen the Black Basta, LockBit, BlackMatter, AvosLocker, REvil, HelloKitty, RansomEXX, and Hive ransomware groups targeting it.
SecurityScorecard’s Attack Surface IntelligenceASI tool reveals that ESXi is, in general, fairly widespread, detecting some version of it in use at 139,491 IP addresses worldwide.
Image 1: Attack Surface IntelligenceASI indicates a fairly wide geographic distribution of ESXi services.
Additionally, Attack Surface IntelligenceASI has identified ninety-two IP addresses attributed to previous ransomware victims where ESXi is also in use; this may reflect other ransomware groups’ targeting of these services prior to the announcement of the ESXiArgs campaign.
Image 2: Attack Surface IntelligenceASI indicates ESXi in use at IP addresses attributed to previous ransomware victims.
Findings: Possibly Affected Services
While other ransomware groups have previously exploited other ESXi vulnerabilities in the past, Attack Surface IntelligenceASI has revealed the three versions of ESXi that this specific vulnerability may affect: V (versions 6.5, 6.7, and 7.0) are in use at seven, eight, and fifty-eight IP addresses respectively.
Images 3-5: Attack Surface IntelligenceASI enabled researchers to narrow their investigation into ESXiArgs to potentially affected versions.
The STRIKE Team then used these Attack Surface IntelligenceASI results to identify IP addresses from which to collect a sample of traffic that may reflect ESXiArgs activity; given European CERTs’ particular concern with ESXiArgs, researchers selected the French, Italian, and British IP addresses where versions 7.0, 6.7, and 6.5 are in use, respectively, in hopes of identifying potential attempts by ransomware groups to target these services.
Findings: Netflow Analysis
STRIKE Team researchers leveraged SecurityScorecard’s exclusive access to global netflow data to analyze a month (January 3-February 3) of traffic involving the potentially affected IP addresses identified by Attack Surface IntelligenceASI (the four French IP addresses where ESXi 7.0 is in use, the Italian IP address where ESXi 6.7 is in use, and the British IP address where ESXi 6.5 is in use). They compared these three samples both to one another and to the samples from previous ransomware investigations. The latter comparison enabled researchers to identify possibly ransomware-linked IP addresses that communicated with these potential targets, while the former enabled researchers to narrow their focus further to those that may specifically have targeted vulnerable ESXi systems, as ESXi is a common trait of the target IP addresses.
The IP address that appears most likely to reflect an attempt by a ransomware group to exploit this vulnerability is 161.47.17[.]28.; Iit not only appeared in all three of the ESXi traffic samples collected in response to the recent advisories, but also appeared in multiple previous STRIKE Team ransomware investigations.
Three IP addresses (, 143.198.7[.]33, 159.89.246[.]130, and 159.89.188[.]11), appeared in both the French and British IP addresses’ traffic samples while also appearing in previous ransomware victims’ traffic samples, two , (41.94.22[.]2 and 131.108.156[.]113), appeared in both the Italian and French IP addresses’ traffic samples as well as previous ransomware victims’ traffic samples, and another two (, 134.213.193[.]62 and 103.235.46[.]191), appeared in both the Italian and British IP addresses’ traffic samples as well as previous ransomware victims’ traffic samples. These overlaps suggest that, of the IP addresses to appear in the possible targets’ traffic samples, these may be especially likely to have been involved in the ESXiArgs campaign. That said, though, without internal visibility into the target networks, STRIKE researchers cannot determine the specific activity this traffic represents with certainty.
In addition to the above, researchers identified 402 other IP addresses that the cybersecurity vendors who contribute to VirusTotal have linked to malicious activity, forty-six other IP addresses that appeared in previous ransomware investigations (but which VirusTotal does not detect), and five IP addresses that communicated with multiple potential target IP addresses but did not appear in previous ransomware investigations. While less likely to specifically be involved with the ESXiArgs campaign, these IP addresses may nonetheless be suspicious. T; they are available in appendices below.
Recommendations
Apply the relevant update to any still-unpatched servers as soon as possible. If, for some reason, you cannot apply the patch, deactivate OpenSLP services (or limit access to them to a list of trusted IP addresses).
- Take the standard precautions against ransomware:
Maintain up-to-date backups of data threat actors may target for encryption;
Only expose services to the wider internet when necessary; and
Consistently monitor network traffic for any unexpected behavior.
Attack Surface Intelligence and Managed Threat Hunting with Cyber Risk Intelligence
In addition to the visibility offered by the new signal in our ratings platform, SecurityScorecard’s other tools and services can support organizations’ efforts to respond to and defend against these vulnerabilities and their exploitation. SecurityScorecard’s new Attack Surface Intelligence (ASI) solution gives you direct access to SecurityScorecard’s deep threat intelligence data through a global tab on the ratings platform and via API, all of which can contribute to improved visibility into internal and external resources, supporting the infrastructure management advised above.
Attack Surface IntelligenceASI analyzes billions of sources to provide deep threat intelligence and visibility into any IP, network, domain, or vendor’s attack surface risk, from a single pane of glass. This helps a variety of customers do more with the petabytes of data that form the basis of SecurityScorecard Ratings, including identifying all of an organization’s connected assets, exposing unknown threats, conducting investigations at scale, and prioritizing vendor remediation with actionable intelligence.
Attack Surface IntelligenceASI is built into SecurityScorecard’s ratings platform through an enhanced Portfolio view or Global search across all Internet assets, leaked credentials, and infections and metadata from the largest malware sinkhole in the world. Access Attack Surface IntelligenceASI today on the SecurityScorecard platform with 20 free search queries per month or request a demo on our website.
SecurityScorecard’s threat research and intelligence services could be the competitive advantage organizations need to stay ahead of fast-moving threat actors like those exploiting these new vulnerabilities. For more custom insights from our team with 100+ years of combined threat research and investigation experience, or more details on these findings, please contact us to discuss our Cyber Risk Intelligence as a Service (CRIaaS) offering. The above investigation can offer a trustworthy but preliminary view of our capabilities. Our team can continue diving into these details, especially with the ability to provide further support by working with on-site staff.
If you believe your organization to be under immediate threat from actors linked to ESXiArgs and other threats like it, SecurityScorecard also provides managed incident response and digital forensics teams as a professional service driven by a large group of former law enforcement and private sector experts with decades of experience in the space. For immediate support from our teams, please contact us.
Appendix: VirusTotal-Detected IP Addresses Communicating with Possible Targets
167[.]99[.]184[.]51
167[.]71[.]16[.]153
41[.]94[.]22[.]2
45[.]232[.]73[.]46
43[.]129[.]33[.]99
104[.]248[.]246[.]104
193[.]57[.]40[.]49
45[.]232[.]73[.]56
143[.]198[.]28[.]117
147[.]182[.]182[.]55
45[.]232[.]73[.]51
146[.]190[.]85[.]130
162[.]243[.]189[.]2
188[.]166[.]160[.]164
46[.]101[.]128[.]25
137[.]184[.]149[.]253
183[.]82[.]13[.]80
137[.]184[.]58[.]169
89[.]248[.]165[.]166
177[.]39[.]196[.]112
167[.]172[.]40[.]239
27[.]0[.]183[.]209
138[.]197[.]32[.]222
217[.]147[.]224[.]94
102[.]220[.]13[.]85
5[.]188[.]87[.]3
138[.]68[.]76[.]27
201[.]150[.]126[.]212
164[.]92[.]176[.]210
134[.]209[.]124[.]226
131[.]108[.]156[.]1
89[.]203[.]249[.]28
97[.]74[.]81[.]123
64[.]225[.]50[.]135
192[.]206[.]6[.]96
161[.]35[.]140[.]163
167[.]172[.]43[.]20
89[.]203[.]150[.]42
131[.]108[.]156[.]113
131[.]221[.]37[.]179
139[.]59[.]47[.]1
177[.]85[.]4[.]41
132[.]255[.]53[.]97
82[.]196[.]7[.]246
134[.]122[.]88[.]171
157[.]230[.]237[.]83
64[.]227[.]3[.]24
138[.]68[.]91[.]192
157[.]230[.]15[.]216
45[.]232[.]73[.]185
159[.]223[.]184[.]185
104[.]131[.]190[.]193
188[.]166[.]58[.]179
162[.]243[.]48[.]133
159[.]223[.]148[.]18
46[.]101[.]175[.]103
157[.]230[.]83[.]80
157[.]230[.]218[.]88
206[.]81[.]24[.]160
159[.]203[.]179[.]230
142[.]93[.]14[.]124
143[.]110[.]183[.]17
209[.]97[.]160[.]227
178[.]128[.]55[.]198
188[.]166[.]146[.]208
159[.]203[.]85[.]196
159[.]65[.]11[.]5
142[.]93[.]116[.]249
206[.]81[.]4[.]81
128[.]199[.]77[.]201
106[.]51[.]3[.]214
138[.]197[.]32[.]150
68[.]183[.]27[.]133
104[.]236[.]7[.]248
165[.]227[.]83[.]174
159[.]65[.]129[.]227
41[.]63[.]1[.]226
84[.]88[.]59[.]1
165[.]22[.]59[.]229
128[.]199[.]154[.]5
14[.]97[.]218[.]174
147[.]182[.]188[.]81
159[.]65[.]154[.]92
161[.]35[.]125[.]167
167[.]71[.]166[.]90
207[.]154[.]215[.]181
134[.]122[.]8[.]241
137[.]184[.]215[.]213
139[.]59[.]105[.]82
170[.]210[.]46[.]4
41[.]93[.]31[.]73
165[.]22[.]16[.]134
46[.]101[.]224[.]184
85[.]152[.]57[.]60
154[.]68[.]232[.]20
138[.]197[.]80[.]24
104[.]236[.]111[.]25
137[.]184[.]135[.]135
142[.]93[.]178[.]56
159[.]223[.]95[.]166
154[.]68[.]225[.]162
164[.]90[.]231[.]253
138[.]197[.]19[.]166
162[.]243[.]237[.]90
138[.]197[.]175[.]169
134[.]122[.]20[.]244
147[.]182[.]145[.]89
103[.]246[.]240[.]28
167[.]71[.]33[.]249
157[.]230[.]34[.]158
61[.]2[.]224[.]84
164[.]92[.]142[.]65
134[.]209[.]162[.]114
45[.]55[.]180[.]7
178[.]128[.]229[.]120
167[.]71[.]170[.]172
142[.]93[.]201[.]51
142[.]93[.]50[.]8
134[.]122[.]74[.]24
104[.]131[.]68[.]23
68[.]183[.]104[.]78
103[.]246[.]240[.]30
188[.]166[.]247[.]82
178[.]62[.]105[.]122
170[.]210[.]203[.]211
206[.]189[.]185[.]21
104[.]248[.]146[.]84
68[.]183[.]170[.]149
174[.]138[.]64[.]63
159[.]89[.]141[.]221
170[.]210[.]83[.]90
178[.]128[.]214[.]153
159[.]65[.]223[.]90
143[.]244[.]172[.]59
104[.]248[.]252[.]80
138[.]197[.]180[.]102
95[.]85[.]34[.]53
206[.]189[.]80[.]198
161[.]35[.]0[.]70
157[.]245[.]218[.]29
174[.]138[.]16[.]16
159[.]65[.]63[.]94
178[.]62[.]17[.]94
137[.]184[.]104[.]77
104[.]131[.]181[.]4
104[.]236[.]78[.]19
165[.]227[.]106[.]20
161[.]35[.]210[.]148
207[.]154[.]241[.]112
165[.]22[.]66[.]147
159[.]65[.]218[.]99
139[.]59[.]27[.]92
64[.]227[.]120[.]10
170[.]210[.]45[.]123
104[.]248[.]20[.]85
134[.]209[.]69[.]41
137[.]184[.]154[.]154
103[.]16[.]202[.]187
147[.]182[.]128[.]252
159[.]65[.]235[.]114
157[.]245[.]195[.]132
139[.]59[.]76[.]127
167[.]99[.]84[.]28
177[.]91[.]79[.]21
137[.]184[.]21[.]86
157[.]245[.]193[.]85
157[.]245[.]207[.]215
128[.]199[.]204[.]124
128[.]199[.]171[.]119
206[.]81[.]9[.]31
46[.]101[.]249[.]11
115[.]113[.]11[.]143
159[.]223[.]80[.]140
159[.]65[.]163[.]42
161[.]35[.]124[.]45
165[.]22[.]181[.]245
165[.]227[.]114[.]124
167[.]172[.]190[.]215
102[.]215[.]196[.]206
128[.]199[.]45[.]37
134[.]209[.]244[.]230
182[.]156[.]1[.]58
157[.]230[.]111[.]25
187[.]243[.]248[.]114
167[.]99[.]15[.]190
134[.]209[.]211[.]170
143[.]110[.]185[.]99
178[.]128[.]29[.]118
64[.]227[.]35[.]112
206[.]189[.]226[.]38
103[.]129[.]108[.]14
134[.]122[.]30[.]150
147[.]182[.]185[.]145
178[.]128[.]248[.]121
104[.]131[.]3[.]1
165[.]22[.]184[.]212
104[.]131[.]249[.]57
142[.]93[.]187[.]197
165[.]227[.]148[.]167
104[.]131[.]39[.]193
128[.]199[.]64[.]114
128[.]199[.]192[.]230
46[.]101[.]49[.]191
161[.]35[.]4[.]85
138[.]68[.]8[.]161
157[.]230[.]229[.]202
68[.]183[.]20[.]198
167[.]99[.]67[.]143
146[.]190[.]27[.]250
37[.]186[.]127[.]96
161[.]35[.]177[.]39
165[.]227[.]193[.]157
188[.]166[.]5[.]84
134[.]209[.]106[.]24
128[.]199[.]194[.]1
157[.]245[.]156[.]72
41[.]63[.]10[.]8
167[.]71[.]196[.]217
41[.]93[.]33[.]2
104[.]248[.]51[.]246
165[.]22[.]55[.]238
164[.]92[.]152[.]140
104[.]248[.]253[.]245
161[.]35[.]152[.]153
134[.]122[.]63[.]199
45[.]114[.]195[.]2
192[.]241[.]169[.]184
157[.]245[.]143[.]248
147[.]182[.]169[.]252
143[.]244[.]161[.]152
143[.]110[.]255[.]245
164[.]90[.]172[.]83
165[.]22[.]221[.]230
139[.]59[.]121[.]188
159[.]223[.]38[.]199
159[.]203[.]81[.]114
184[.]168[.]122[.]62
162[.]243[.]80[.]57
159[.]223[.]97[.]88
138[.]197[.]162[.]56
104[.]131[.]185[.]48
167[.]99[.]239[.]101
147[.]182[.]218[.]64
134[.]122[.]72[.]235
128[.]199[.]253[.]34
47[.]241[.]223[.]102
61[.]2[.]241[.]214
107[.]170[.]39[.]69
165[.]227[.]133[.]23
167[.]172[.]132[.]44
64[.]227[.]28[.]246
165[.]227[.]196[.]30
68[.]183[.]105[.]114
188[.]166[.]14[.]99
143[.]198[.]116[.]232
167[.]71[.]28[.]141
62[.]149[.]128[.]154
178[.]62[.]36[.]171
128[.]199[.]146[.]3
202[.]160[.]145[.]243
45[.]191[.]91[.]45
46[.]101[.]187[.]42
188[.]166[.]39[.]184
167[.]172[.]141[.]86
150[.]165[.]37[.]44
128[.]199[.]84[.]25
139[.]59[.]120[.]201
146[.]164[.]51[.]48
165[.]22[.]246[.]63
165[.]22[.]234[.]248
200[.]137[.]65[.]37
68[.]183[.]31[.]114
200[.]137[.]5[.]196
202[.]83[.]16[.]8
147[.]182[.]190[.]189
187[.]86[.]135[.]246
165[.]227[.]202[.]89
157[.]230[.]127[.]240
207[.]154[.]226[.]163
159[.]223[.]92[.]245
157[.]245[.]212[.]8
138[.]197[.]103[.]160
142[.]93[.]77[.]1
167[.]99[.]152[.]121
159[.]65[.]188[.]65
47[.]254[.]21[.]33
157[.]230[.]208[.]92
104[.]236[.]228[.]230
45[.]55[.]134[.]210
62[.]149[.]128[.]163
104[.]248[.]127[.]185
128[.]199[.]32[.]98
134[.]122[.]114[.]136
167[.]99[.]218[.]101
157[.]230[.]84[.]180
188[.]166[.]95[.]44
104[.]236[.]94[.]202
111[.]93[.]191[.]170
68[.]183[.]132[.]99
183[.]82[.]96[.]133
159[.]65[.]242[.]16
46[.]101[.]2[.]4
165[.]22[.]186[.]178
167[.]172[.]187[.]120
161[.]35[.]71[.]152
104[.]248[.]242[.]125
167[.]71[.]16[.]158
67[.]205[.]167[.]168
128[.]199[.]97[.]155
178[.]128[.]209[.]69
128[.]199[.]142[.]208
45[.]232[.]73[.]83
165[.]90[.]14[.]164
128[.]199[.]247[.]226
64[.]227[.]67[.]194
189[.]177[.]201[.]48
68[.]183[.]127[.]157
143[.]198[.]191[.]25
159[.]223[.]120[.]180
64[.]227[.]25[.]222
128[.]199[.]148[.]70
162[.]243[.]172[.]239
142[.]93[.]245[.]58
167[.]172[.]243[.]183
64[.]225[.]19[.]94
167[.]71[.]169[.]21
159[.]203[.]179[.]44
138[.]68[.]102[.]83
164[.]92[.]193[.]67
159[.]65[.]6[.]45
198[.]199[.]72[.]47
67[.]207[.]83[.]228
134[.]209[.]175[.]24
206[.]189[.]232[.]29
142[.]93[.]241[.]93
200[.]17[.]114[.]130
147[.]139[.]45[.]22
139[.]59[.]14[.]115
67[.]205[.]171[.]223
164[.]92[.]189[.]191
52[.]199[.]105[.]183
62[.]149[.]128[.]74
198[.]148[.]92[.]176
104[.]248[.]179[.]42
139[.]59[.]187[.]229
138[.]197[.]97[.]212
67[.]205[.]144[.]9
41[.]89[.]196[.]16
159[.]65[.]183[.]47
207[.]154[.]244[.]8
157[.]230[.]23[.]46
45[.]55[.]134[.]67
64[.]225[.]20[.]153
13[.]212[.]228[.]23
167[.]172[.]243[.]126
157[.]245[.]138[.]97
212[.]62[.]96[.]86
43[.]153[.]2[.]147
167[.]172[.]146[.]169
178[.]128[.]87[.]65
165[.]227[.]194[.]124
157[.]230[.]133[.]15
165[.]22[.]190[.]39
18[.]142[.]120[.]133
134[.]209[.]107[.]178
174[.]138[.]23[.]45
192[.]241[.]182[.]74
167[.]71[.]160[.]75
103[.]134[.]44[.]42
206[.]81[.]16[.]240
138[.]197[.]6[.]174
178[.]128[.]195[.]69
103[.]83[.]158[.]66
159[.]223[.]221[.]95
143[.]110[.]217[.]201
137[.]184[.]111[.]153
62[.]149[.]128[.]157
143[.]198[.]182[.]160
62[.]149[.]128[.]160
178[.]128[.]167[.]226
113[.]190[.]245[.]2
103[.]235[.]46[.]191
103[.]82[.]242[.]27
147[.]182[.]173[.]182
52[.]221[.]209[.]153
134[.]209[.]218[.]186
64[.]227[.]77[.]252
164[.]92[.]179[.]157
203[.]115[.]99[.]220
143[.]198[.]33[.]14
198[.]199[.]86[.]89
134[.]209[.]119[.]196
159[.]203[.]92[.]179
134[.]209[.]212[.]251
45[.]55[.]42[.]227
138[.]185[.]172[.]129
103[.]210[.]44[.]190
69[.]164[.]45[.]0
168[.]167[.]69[.]86
159[.]65[.]255[.]251
193[.]0[.]14[.]129
64[.]225[.]16[.]177
Appendix: IP Addresses From Previous Ransomware Investigations
107[.]167[.]20[.]230
192[.]33[.]214[.]47
130[.]59[.]35[.]198
167[.]71[.]87[.]161
104[.]131[.]15[.]126
164[.]90[.]143[.]171
143[.]198[.]7[.]93
64[.]225[.]9[.]37
157[.]230[.]89[.]254
134[.]209[.]219[.]19
138[.]197[.]0[.]92
146[.]20[.]132[.]153
146[.]20[.]132[.]141
103[.]155[.]16[.]129
157[.]230[.]93[.]231
177[.]66[.]152[.]137
184[.]106[.]10[.]72
184[.]106[.]10[.]77
192[.]241[.]189[.]146
195[.]176[.]26[.]206
159[.]203[.]145[.]121
167[.]172[.]26[.]233
23[.]253[.]188[.]26
146[.]190[.]223[.]190
192[.]241[.]157[.]60
185[.]14[.]184[.]154
64[.]225[.]1[.]58
143[.]244[.]220[.]80
64[.]185[.]181[.]238
165[.]22[.]12[.]234
130[.]60[.]204[.]10
162[.]242[.]174[.]138
162[.]13[.]32[.]69
146[.]20[.]128[.]191
162[.]13[.]202[.]201
146[.]20[.]128[.]116
138[.]197[.]155[.]84
138[.]197[.]63[.]78
192[.]241[.]243[.]218
64[.]15[.]159[.]210
68[.]183[.]118[.]126
159[.]223[.]180[.]245
137[.]184[.]213[.]124
186[.]237[.]182[.]226
177[.]66[.]152[.]139
85[.]13[.]90[.]185
Appendix: IP Addresses Communicating With Multiple Potential Target IP Addresses
104[.]236[.]65[.]181
68[.]183[.]136[.]212
159[.]65[.]249[.]246
134[.]122[.]88[.]171
45[.]172[.]198[.]114