This report is provided “as is” for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained herein. The DHS does not endorse any commercial product or service referenced in this bulletin or otherwise.

This document is marked TLP:WHITE–Disclosure is not limited. Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction. For more information on the Traffic Light Protocol (TLP), see http://www.cisa.gov/tlp.

Description

Since December 2021, multiple threat actor groups have exploited Log4Shell on unpatched, public-facing VMware Horizon and Unified Access Gateway (UAG) servers. From May through June 2022, CISA provided remote incident support at an organization where CISA observed suspected Log4Shell PowerShell downloads. During remote support, CISA confirmed the organization was compromised by malicious cyber actors who exploited Log4Shell in a VMware Horizon server that did not have patches or workarounds applied. CISA analyzed five malware samples obtained from the organization’s network: two malicious PowerShell files, two Extensible Markup Language (XML) files, and a 64-bit compiled Python Portable Executable (PE) file.

The two PowerShell files are Trojan downloaders designed to download malicious files from a command and control (C2) server and install them on the compromised system. One of the scripts also checks for and installs Nmap if it is not installed on the compromised system. The two XML files are for scheduling tasks for persistence. The 64-bit compiled Python PE file is designed to perform scans for IP addresses of live hosts, open ports, and services running on those hosts.

For more information on Log4Shell, see: 

For a downloadable copy of IOCs, see: MAR-10386789-1.v1.stix.

Submitted Files (5)

1d459b9909adf98690635c62ea005009ede8eb9a665b8703fe2ad0b0c414816b (this.ps1)

4cdd06a36858ac32a09606bfecb54b517ad41a6aac1e37ca56bb1c193f8174cf (RuntimeService.exe)

76a2979d965d42f99558ca6ecd97734697249667291a3013d611e310a03f550e (ps.ps1)

c357879e2c1013dcf999bcdc65372eacf0895af4a4b4bad2b7d28108d3e7c46a (this.xml)

e3d2e6b5cd422de1be7e6aa830b91115d204ba5e87c77b6431f3313e0930a697 (that.xml)

Additional Files (8)

3b4d726bd366e7439367fa78a186dfa9b641d3b2ad354fd915581b6567480f94 (nmap.exe)

407d60626707baee29fb9f2597dd32cfd544ff46df7f76e51ff0b79b3ffce3f2 (this.xml)

42c844c62ad1b7ae1925973a9b6845b40d4f626a4895cba9ae9e3e3de3f7973a (n.zip)

6408217e10fac9f6549ffaaab328bcfeed4a7ebea71f3dcf60f6186e1b21b501 (that.xml)

817046c4fe89cd44dbb613cdac2f0c165e2b47d2b5245911ca6fabdda89d1691 (this.ps1)

b050749c87399f9978cc6eaea7d25405fc0d099a14c169f5c5f63b8b6ec98b0f (RuntimeService.exe)

e6bc8aa44233312058704b4d5954c45b4160841f470dd7f6d13c08940e61a7bb (ps.ps1)

fb833ecd1b1050304f364f879b8b1f7b7136e9c4a21aaf0a6c6b3f419e892d6d (elasticsearch.nse)

IPs (1)

66.70.238.65

1d459b9909adf98690635c62ea005009ede8eb9a665b8703fe2ad0b0c414816b

Tags

downloaderloadertrojan

Details

Antivirus

YARA Rules

• rule CISA_10386789_01 : downloader
  {
     meta:
         Author = “CISA Code & Media Analysis”
         Incident = “10386789”
         Date = “2022-06-08”
         Last_Modfied = “20220613_1130”
         Actor = “n/a”
         Category = “Downloader”
         Family = “n/a”
         Description = “Detects PowerShell downloader samples”
         MD5_1 = “8aedb094121903a3bfc3dade34f48126”
         SHA256_1 = “1d459b9909adf98690635c62ea005009ede8eb9a665b8703fe2ad0b0c414816b”
         MD5_2 = “1940ddb77882162f898bc3aae9c67d94”
         SHA256_2 = “817046c4fe89cd44dbb613cdac2f0c165e2b47d2b5245911ca6fabdda89d1691”
         MD5_3 = “84aadb11699f0c3ed062f484aa0a622e”
         SHA256_3 = “e6bc8aa44233312058704b4d5954c45b4160841f470dd7f6d13c08940e61a7bb”
         MD5_4 = “a439e7a030d52c8d31bf2c140ccf216b”
         SHA256_4 = “76a2979d965d42f99558ca6ecd97734697249667291a3013d611e310a03f550e”
     strings:
         $s0 = { 44 6F 63 75 6D 65 6E 74 73 5C 70 73 2E 70 73 31 }
         $s1 = { 44 6F 77 6E 6C 6F 61 64 73 5C 65 6C 61 73 74 69 63 73 65 61 72 63 68 2E 6E 73 65 }
         $s2 = { 5C 55 6E 69 6E 73 74 61 6C 6C 5C 4E 70 63 61 70 49 6E 73 74 }
         $s3 = { 5C 55 6E 69 6E 73 74 61 6C 6C 5C 4E 6D 61 70 }
         $s4 = { 2F 44 65 6C 65 74 65 20 2F 74 6E 20 22 52 75 6E 74 69 6D 65 20 53 65 72 76 69 63 65 22 }
         $s5 = { 44 6F 77 6E 6C 6F 61 64 73 5C 6E 2E 7A 69 70 22 }
         $s6 = { 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 52 75 6E 74 69 6D 65 20 55 70 64 61 74 65 20 53 65 72 76 69 63 65 }
         $s7 = { 44 6F 77 6E 6C 6F 61 64 73 5C 6E 6D 61 70 2E 65 78 65 22 }
         $t8 = { 6D 61 74 63 68 20 22 73 79 73 74 65 6D 70 72 6F 66 69 6C 65 }
         $t9 = { 2D 6E 6F 74 6D 61 74 63 68 20 22 41 70 70 44 61 74 61 }
         $t10 = { 20 6B 69 6C 6C 20 2D 49 64 20 }
         $t11 = { 2F 52 75 6E 20 2F 74 6E 20 22 52 75 6E 74 69 6D 65 20 53 65 72 76 69 63 65 }
         $t12 = { 44 6F 77 6E 6C 6F 61 64 73 5C 74 68 69 73 2E 70 73 31 }
     condition:
         all of ($s*) or all of ($t*)
  }

ssdeep Matches

No matches found.

Relationships

Description

This artifact is a malicious PowerShell script file downloaded and installed by “ps.ps1” (a439e7a030d52c8d31bf2c140ccf216b) . When executed, it stops and deletes the running scheduled tasks below if they exist on the compromised system:

–Begin task name–
“Runtime Service”
“MicrosoftWindowsRuntime Update Service”
–End task name–

It downloads and installs a scheduled task XML file and a PowerShell file below if the file “C:Program Files (x86)NmapRuntimeService.exe” is installed on the compromised system:

–Begin files–
C:UsersPublicDownloadsthat.xml ==> “9bf865e73bb0bf021af2d4a2ce1abdfe”
C:UsersPublicDocumentsps.ps1 ==> “a439e7a030d52c8d31bf2c140ccf216b”
–End files–

It creates a scheduled task named “MicrosoftWindowsRuntime Update Service” from the task specified in the above XML file to execute the file “C:UsersPublicDocumentsps.ps1” at a specified time of each day for persistence, and then exits it code execution.

Displayed below is the command used to install the scheduled task named “MicrosoftWindowsRuntime Update Service”:

–Begin scheduled task–
“schtasks.exe /Create /XML “C:UsersPublicDownloadsthat.xml” /tn “MicrosoftWindowsRuntime Update Service”
–End scheduled task–

If not, it checks if the Nmap file path “C:Program Files (x86)Nmap” is installed on the victim’s system. If the file path exists, it will search for the running process named “RuntimeService”, which is the 64-bit Python compiled PE file. It will attempt to terminate and delete it from “C:Program Files (x86)NmapRuntimeService.exe” if the file is running. It downloads and installs a scheduled task XML file and the Python compiled PE file. It copies the PE file from “C:UsersPublicDownloadsRuntimeService.exe” to the Nmap installed folder “C:Program Files (x86)NmapRuntimeService.exe”.

Displayed below are the scheduled task XML file and PE file installed at runtime:

–Begin files–
C:UsersPublicDownloadsthis.xml ==> “e4ea99b9a35807bae6bc2885b220c498”
C:UsersPublicDownloadsRuntimeService.exe ==> copied to C:Program Files (x86)NmapRuntimeService.exe. ==> “eda057d006561e28563813b2e81b9fd0”
–End files–

It creates a scheduled task named “Runtime Service” from the task specified in the above “this.xml” file on the victim’s system to execute the PE file “C:Program Files (x86)NmapRuntimeService.exe” with predefined arguments in every system reboot for persistence.

Displayed below is the command used to install the scheduled task named “Runtime Service”:

–Begin scheduled task–
“schtasks.exe /Create /XML “C:UsersPublicDownloadsthis.xml” /tn “Runtime Service”
–End scheduled task–

If the Nmap file path “C:Program Files (x86)Nmap” is not installed on the victim’s system, it will download a zip file from its C2 server to “C:UsersPublicDownloadsn.zip”. The zip file contains the Nmap installer and the NSE file. It installs the Nmap installer on the compromised system with the command below:

–Begin command–
start “C:UsersPublicDownloadsNmap.exe” “/S”
–End command–

It will download the these files RuntimeService.exe, this.xml, that.xml, and ps.ps1 files from its C2 server into “C:UsersPublicDownloads”.

It copies the NSE file from the current directory “C:UsersPublicDownloadselasticsearch.nse” to “C:Program Files (x86)Nmapscriptselasticsearch.nse”, and the Python PE file “C:UsersPublicDownloadsRuntimeService.exe” to “C:Program Files (x86)NmapRuntimeService.exe”. It creates scheduled tasks named “Runtime Service” and “Runtime Update Service” from the task specified in the above XML files on the victim’s system for persistence.

It deletes the command line for removing the Nmap application and the Nmap project’s packet capture (Npcap) installed from the registry by changing the “UninstallString” registry value to a null string under the following registry keys:

–Begin registry entries–
“HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionUninstallNpcapInst”
“UninstallString”=”C:Program FilesNpcapuninstall.exe”

“HKEY_LOCAL_MACHINESOFTWAREWOW6432NodeMicrosoftWindowsCurrentVersionUninstallNmap”
“UninstallString” = “C:Program Files (x86)Nmapuninstall.exe”
–End registry entries–

It deletes the files below from the victim’s system:

–Begin files–
C:UsersPublicDownloadsnmap.exe
C:UsersPublicDownloadselasticsearch.nse
C:UsersPublicDownloadsn.zip
C:UsersPublicDownloadsRuntimeService.exe
C:UsersPublicDownloadsthis.xml
C:UsersPublicDownloadsthat.xml”
–End files–

Displayed below are the list of Uniform Resource Identifiers (URIs) used to download the files above:

–Begin URIs–
http[:]//66[.]70[.]238[.]65/RuntimeService.exe
http[:]//66[.]70[.]238[.]65/this.xml
http[:]//66[.]70[.]238[.]65/that.xml
http[:]//66[.]70[.]238[.]65/ps.ps1
http[:]//66[.]70[.]238[.]65/n.zip
–End URIs–

Screenshots

76a2979d965d42f99558ca6ecd97734697249667291a3013d611e310a03f550e

Tags

downloaderloadertrojan

Details

Antivirus

YARA Rules

• rule CISA_10386789_01 : downloader
  {
     meta:
         Author = “CISA Code & Media Analysis”
         Incident = “10386789”
         Date = “2022-06-08”
         Last_Modfied = “20220613_1130”
         Actor = “n/a”
         Category = “Downloader”
         Family = “n/a”
         Description = “Detects PowerShell downloader samples”
         MD5_1 = “8aedb094121903a3bfc3dade34f48126”
         SHA256_1 = “1d459b9909adf98690635c62ea005009ede8eb9a665b8703fe2ad0b0c414816b”
         MD5_2 = “1940ddb77882162f898bc3aae9c67d94”
         SHA256_2 = “817046c4fe89cd44dbb613cdac2f0c165e2b47d2b5245911ca6fabdda89d1691”
         MD5_3 = “84aadb11699f0c3ed062f484aa0a622e”
         SHA256_3 = “e6bc8aa44233312058704b4d5954c45b4160841f470dd7f6d13c08940e61a7bb”
         MD5_4 = “a439e7a030d52c8d31bf2c140ccf216b”
         SHA256_4 = “76a2979d965d42f99558ca6ecd97734697249667291a3013d611e310a03f550e”
     strings:
         $s0 = { 44 6F 63 75 6D 65 6E 74 73 5C 70 73 2E 70 73 31 }
         $s1 = { 44 6F 77 6E 6C 6F 61 64 73 5C 65 6C 61 73 74 69 63 73 65 61 72 63 68 2E 6E 73 65 }
         $s2 = { 5C 55 6E 69 6E 73 74 61 6C 6C 5C 4E 70 63 61 70 49 6E 73 74 }
         $s3 = { 5C 55 6E 69 6E 73 74 61 6C 6C 5C 4E 6D 61 70 }
         $s4 = { 2F 44 65 6C 65 74 65 20 2F 74 6E 20 22 52 75 6E 74 69 6D 65 20 53 65 72 76 69 63 65 22 }
         $s5 = { 44 6F 77 6E 6C 6F 61 64 73 5C 6E 2E 7A 69 70 22 }
         $s6 = { 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 52 75 6E 74 69 6D 65 20 55 70 64 61 74 65 20 53 65 72 76 69 63 65 }
         $s7 = { 44 6F 77 6E 6C 6F 61 64 73 5C 6E 6D 61 70 2E 65 78 65 22 }
         $t8 = { 6D 61 74 63 68 20 22 73 79 73 74 65 6D 70 72 6F 66 69 6C 65 }
         $t9 = { 2D 6E 6F 74 6D 61 74 63 68 20 22 41 70 70 44 61 74 61 }
         $t10 = { 20 6B 69 6C 6C 20 2D 49 64 20 }
         $t11 = { 2F 52 75 6E 20 2F 74 6E 20 22 52 75 6E 74 69 6D 65 20 53 65 72 76 69 63 65 }
         $t12 = { 44 6F 77 6E 6C 6F 61 64 73 5C 74 68 69 73 2E 70 73 31 }
     condition:
         all of ($s*) or all of ($t*)
  }

ssdeep Matches

No matches found.

Relationships

Description

This artifact is a malicious PowerShell script file downloaded and installed by “this.ps1” (8aedb094121903a3bfc3dade34f48126) and “ps.ps1” (a439e7a030d52c8d31bf2c140ccf216b). This file and “84aadb11699f0c3ed062f484aa0a622e” have similar code functions. When executed, it checks and stops any process running from the specified paths:

–Begin file paths–
C:WindowsTemp
C:WindowsSystem32configsystemprofile
–End file paths–

If not, it checks if the scheduled task named “Runtime Service” is installed on the victim’s system. If not, it downloads and installs the XML scheduled task file “C:UsersPublicDownloadsthis.xml” (e4ea99b9a35807bae6bc2885b220c498) and creates a scheduled task named “Runtime Service” from the task specified in the XML file on the victim’s system. This task is designed to run the file “C:Program Files (x86)NmapRuntimeService.exe” with predefined arguments in every system reboot.

It checks if the scheduled task named “MicrosoftWindowsRuntime Update Service” is installed on the victim’s system. If not, it downloads and installs the XML scheduled task file “C:UsersPublicDownloadsthat.xml” (9bf865e73bb0bf021af2d4a2ce1abdfe) and creates a scheduled task named “MicrosoftWindowsRuntime Update Service” from the task specified in the XML file on the victim’s system. This task is designed to run the PowerShell script file from “C:UsersPublicDocumentsps.ps1” in a specified date and time.

It checks if the Nmap file path “C:Program Files (x86)Nmap” is installed on the victim’s system. If the file path is not installed, it downloads a PowerShell file from its C2 server to “C:UsersPublicDownloadsthis.ps1” (8aedb094121903a3bfc3dade34f48126) before executing it using the command below:

–Begin command–
“Powershell.exe -ExecutionPolicy UnRestricted -File “C:UsersPublicDownloadsthis.ps1”
–End command–

If the Nmap file path is installed, it checks if the PE file “C:Program Files (x86)NmapRuntimeService.exe” (eda057d006561e28563813b2e81b9fd0) is also installed on the victim’s system. If the PE file is not installed, it downloads and installs the PE file into “C:UsersPublicDownloadsRuntimeService.exe” (eda057d006561e28563813b2e81b9fd0) if the PE file is not installed on the victim’s system. It copies the PE file from “C:UsersPublicDownloadsRuntimeService.exe” to the Nmap file path “C:Program Files (x86)NmapRuntimeService.exe”. It enables and runs the scheduled task named “Runtime Service” to execute the PE file “C:Program Files (x86)NmapRuntimeService.exe”.

If the PE file is installed, it will attempt to retrieve and verify the last write time of the file with the date and time: “Sunday, April 24, 2022 11:31:45 AM” retrieved from the C2 server using the hard-coded URI:”http[:]//66[.]70[.]238[.]65/txt.txt”.

Analysis indicates that if the last write time of the file is less than the date and time retrieved from the C2 server, it will search for the running process named “RuntimeService” and attempt to terminate and delete it from “C:Program Files (x86)NmapRuntimeService.exe” if the file is running on the victim’s system. It downloads and installs the PE file into “C:UsersPublicDownloadsRuntimeService.exe”. It copies the PE file from “C:UsersPublicDownloadsRuntimeService.exe” to the Nmap file path “C:Program Files (x86)NmapRuntimeService.exe”. It enables and runs the scheduled task named “Runtime Service” to execute the PE file “C:Program Files (x86)NmapRuntimeService.exe”.

It is designed to delete the other files below before existing its code execution:

–Begin deleted files–
“C:UsersPublicDownloadsRuntimeService.exe”
“C:UsersPublicDownloadsthis.xml”
“C:UsersPublicDownloadsthat.xml”
“C:UsersPublicDownloadsthis.ps1”
–End deleted files–

Displayed below are the URIs used to download the files above:

–Begin URIs–
http[:]//66[.]70[.]238[.]65/RuntimeService.exe
http[:]//66[.]70[.]238[.]65/this.xml
http[:]//66[.]70[.]238[.]65/that.xml
http[:]//66[.]70[.]238[.]65/this.ps1
–End URIs–

Screenshots

e3d2e6b5cd422de1be7e6aa830b91115d204ba5e87c77b6431f3313e0930a697

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Relationships

Description

This artifact is the scheduled task XML file downloaded and installed by “8aedb094121903a3bfc3dade34f48126” and “a439e7a030d52c8d31bf2c140ccf216b”. It contains the task’s properties, triggers, actions, conditions, and settings used to create a scheduled task named “MicrosoftWindowsRuntime Update Service” for persistence. It is designed to execute the PowerShell script file from “C:UsersPublicDocumentsps.ps1” in everyday from January 01, 2022. This file and “80343fb39fe8657f3f3904509b59d1d2” have similar code functions.

Screenshots

c357879e2c1013dcf999bcdc65372eacf0895af4a4b4bad2b7d28108d3e7c46a

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Relationships

Description

This artifact is the scheduled task XML file downloaded and installed by “8aedb094121903a3bfc3dade34f48126” and “a439e7a030d52c8d31bf2c140ccf216b”. This file and “d5e111c8cea4d2c8e8ae15a570ff8d3d” have similar code functions. It contains the task’s properties, triggers, actions, conditions, and settings used to create a scheduled task named “Runtime Service” for persistence. It is designed to execute the Python compiled PE file from “C:Program Files (x86)NmapRuntimeService.exe” with the arguments below in every system reboot.

–Begin arguments–
[C2 server IP address] [Port number] [threads]
66[.]70[.]238[.]65 50106 250
–End arguments–

Screenshots