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Malware Analysis Report




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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 (

6408217e10fac9f6549ffaaab328bcfeed4a7ebea71f3dcf60f6186e1b21b501 (that.xml)

817046c4fe89cd44dbb613cdac2f0c165e2b47d2b5245911ca6fabdda89d1691 (this.ps1)

b050749c87399f9978cc6eaea7d25405fc0d099a14c169f5c5f63b8b6ec98b0f (RuntimeService.exe)

e6bc8aa44233312058704b4d5954c45b4160841f470dd7f6d13c08940e61a7bb (ps.ps1)

fb833ecd1b1050304f364f879b8b1f7b7136e9c4a21aaf0a6c6b3f419e892d6d (elasticsearch.nse)

IPs (1)





Name this.ps1
Size 7962 bytes
Type ASCII text, with very long lines, with CRLF line terminators
MD5 8aedb094121903a3bfc3dade34f48126
SHA1 ed1aad906c2d63c8593708fb685655b891a02854
SHA256 1d459b9909adf98690635c62ea005009ede8eb9a665b8703fe2ad0b0c414816b
SHA512 2c09fb3defdd4810c89d3acaa57fdf3fd1ca9cffe6db43bab73bc629db817d273254be9c35d9cdb161cd0f9c35f5537efafe68bf83d7adb7d022600fd26e6e89
ssdeep 192:Ki17MYm59jl5VlxN17MYmoFW2SvjkrvVlxN17MYm7rY2E2/:KIwZ99wnZ2wbrY9W
Entropy 5.256359
Path C:UsersPublicDownloadsthis.ps1
ESET PowerShell/TrojanDownloader.Agent.EQN trojan
YARA Rules
  • rule CISA_10386789_01 : downloader
           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”
           $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 }
           $t12 = { 44 6F 77 6E 6C 6F 61 64 73 5C 74 68 69 73 2E 70 73 31 }
           all of ($s*) or all of ($t*)
ssdeep Matches

No matches found.

1d459b9909… Contains
1d459b9909… Connected_To
1d459b9909… Downloaded e3d2e6b5cd422de1be7e6aa830b91115d204ba5e87c77b6431f3313e0930a697
1d459b9909… Downloaded c357879e2c1013dcf999bcdc65372eacf0895af4a4b4bad2b7d28108d3e7c46a
1d459b9909… Downloaded 4cdd06a36858ac32a09606bfecb54b517ad41a6aac1e37ca56bb1c193f8174cf
1d459b9909… Downloaded 42c844c62ad1b7ae1925973a9b6845b40d4f626a4895cba9ae9e3e3de3f7973a
1d459b9909… Downloaded 76a2979d965d42f99558ca6ecd97734697249667291a3013d611e310a03f550e

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 “”. 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–
“UninstallString”=”C:Program FilesNpcapuninstall.exe”

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

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

–Begin files–
–End files–

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

–Begin URIs–
–End URIs–