MAR-251132.c1.v1 Exploitation of SharePoint Vulnerabilities

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:CLEAR--Recipients may share this information without restriction. Sources may use TLP:CLEAR 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:CLEAR information may be shared without restriction. For more information on the Traffic Light Protocol (TLP), see http://www.cisa.gov/tlp.

Description

CISA received six files related to Microsoft SharePoint vulnerabilities: CVE-2025-49704 [CWE-94: Code Injection], CVE-2025-49706 [CWE-287: Improper Authentication], CVE-2025-53770 [CWE-502: Deserialization of Trusted Data], and CVE-2025-53771 [CWE-287: Improper Authentication]. According to Microsoft, cyber threat actors have chained CVE-2025-49706 (a network spoofing vulnerability) and CVE-2025-49704 (a remote code execution (RCE) vulnerability) in an exploit chain known as “ToolShell” to gain unauthorized access to on-premise SharePoint servers. Microsoft has not confirmed exploitation of CVE-2025-53771; however, CISA assesses exploitation is likely because it can be chained with CVE-2025-53770 to bypass previously disclosed vulnerabilities CVE-2025-49704 and 
CVE-2025-49706. 

The analysis includes two Base64 encoded .NET Dynamic-link Library (DLL) binaries and four Active Server Page Extended [ASPX] files. The decoded DLLs are designed to retrieve machine key settings within an ASP[.]NET application's configuration and add the retrieved machine key values to the Hypertext Transfer Protocol (HTTP) response header. 

The first ASPX file is used to retrieve and output machine key information from an ASP[.]NET application’s configuration. The next ASPX file contains a command-line instruction used to execute a PowerShell command. The PowerShell command is designed to Base64 decode and install a malicious ASPX webshell on disk. The webshell is used to handle various web-related operations, including setting and retrieving HTTP cookies, command execution and uploading files. The remaining two ASPX webshells are used to execute a command using PowerShell on the server. 

CISA encourages organizations to use the indicators of compromise (IOCs) and detection signatures in this Malware Analysis Report to identify malware samples. For more information on these CVEs, see CISA Alert Microsoft Releases Guidance on Exploitation of SharePoint Vulnerabilities.

Download the PDF version of this report:

• MAR-251132.c1.v1 (PDF, 2.03 MB )

For a downloadable copy of IOCs associated with this MAR, see:

• MAR-251132.c1.v1.CLEAR_stix2 (JSON, 84.95 KB )

For a downloadable copy of the SIGMA rules associated with this MAR, see version in .pdf or .yaml format: 

• CMA_SIGMA_251132_CVE_2025_53770_ToolShell_IOCs (PDF, 42.50 KB )
• CMA SIGMA 251132 (YAML, 5.55 KB )
• CMA_SIGMA_251132_1_CVE_2025_53770_ToolShell (PDF, 41.03 KB )
• CMA SIGMA 251132 1 (YAML, 4.22 KB )
• CMA_SIGMA_251132_2_CVE_2025_53770_ToolShell (PDF, 39.79 KB )
• CMA SIGMA 251132 2 (YAML, 2.86 KB )

Submitted Files (6)

3461da3a2ddcced4a00f87dcd7650af48f97998a3ac9ca649d7ef3b7332bd997 (osvmhdfl.dll)

60a37499f9b02c203af24c2dfd7fdb3834cea707c4c56b410a7e68376938c4b7 (stage3.txt)

92bb4ddb98eeaf11fc15bb32e71d0a63256a0ed826a03ba293ce3a8bf057a514 (spinstall0.aspx)

9340bf7378234db5bca0dc5378bf764b6a24bb87a42b05fa21a996340608fbd7 (info3.aspx)

d0c4d6a4be0a65f8ca89e828a3bc810572fff3b3978ff0552a8868c69f83d170 (spinstallp.aspx)

d9c4dd5a8317d1d83b5cc3482e95602f721d58e3ba624d131a9472f927d33b00 (spinstallb.aspx)

Additional Files (2)

675a10e87c248d0f629da864ba8b7fd92b62323c406a69dec35a0e6e1552ecbc (info3.aspx)

bee94b93c1796981a55d7bd27a32345a61304a88ed6cd70a5f7a402f1332df72 (bjcloiyq.dll)

60a37499f9b02c203af24c2dfd7fdb3834cea707c4c56b410a7e68376938c4b7

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_01 : steals_authentication_credentials exfiltrates_data
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250724_721"
         actor = "n/a"
         family = "n/a"
         capabilities = "steals-authentication-credentials exfiltrates-data"
         malware_type = "unknown"
         tool_type = "unknown"
         description = "Detects Encoded .Net DLL samples"
         sha256_1 = "60a37499f9b02c203af24c2dfd7fdb3834cea707c4c56b410a7e68376938c4b7"
     strings:
         $s0 = { 4E 62 32 52 6C 41 46 4E 30 63 6D 6C 75 5A 77 42 44 62 32 35 6A 59 58 51 }
         $s1 = { 41 45 41 55 77 42 30 41 48 49 41 61 51 42 75 41 47 63 41 52 67 42 70 41 }
         $s2 = { 59 58 52 76 63 6D 41 79 57 31 74 54 65 58 4E 30 5A 57 30 75 51 6E 6C 30 }
         $s3 = { 4A 7A 61 57 39 75 50 54 51 75 4D 43 34 77 4C 6A 41 73 49 45 4E 31 62 48 }
         $s4 = { 43 42 57 5A 58 4A 7A 61 57 39 75 50 54 51 75 4D 43 34 77 4C 6A 41 73 49 }
         $s5 = { 4D 54 6B 7A 4E 47 55 77 4F 44 6C 64 58 53 42 48 5A 58 52 46 62 6E 56 74 }
         $s6 = { 5A 58 4A 68 64 47 39 79 4B 43 6B 49 41 41 41 41 43 67 46 }
         $s7 = { 54 65 58 4E 30 5A 57 30 75 52 6E 56 75 59 32 41 79 57 31 }
         $s8 = { 74 54 65 58 4E 30 5A 57 30 75 51 32 39 73 62 47 56 6A 64 47 6C 76 62 6E 4D 75 52 }
     condition:
         all of them
  }
   

SIGMA Rule

                             ## CISA Code & Media Analysis ##

                           ############ README ###############
## Edit rules and queries as needed for your hunt and based on your environment.
## Ensure your EDR/SIEM instance has enough memory to run these AND/OR condition based queries. May take longer to run than conventional Sigma rule query. 
## Do not edit "logsource-product:" unless you are editing this rule to meet specific logsources/fields and know your environment.
## TLP GREEN + Please use local installation of Sigma to convert this rule.
## TLP CLEAR may convert rules using online converter of choice.
                           ###################################

title: Detects ToolShell CVE-2025-53770 Exploitation IOCs and Activity
incident: 251133.r1
tlp: CLEAR
id: aba8967f-6613-47a8-87d1-e5d7aae31e9b
status: test
description: Detects ToolShell CVE-2025-53770 Exploitation of SharePoint servers. Previous related CVEs are CVE-2025-49706 and CVE-2025-49704. CVE-2025-53770 is new and stealthy webshell called SharpyShell, that extracts and leaks cryptographic secrets from the SharePoint server using a simple GET request.
references:
   - https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770
   - https://research.eye.security/sharepoint-under-siege/
   - https://x.com/codewhitesec/status/1944743478350557232/photo/1
   - 251132.r1
author: CISA Code & Media Analysis
date: 2025-07-21
modified: 2025-07-22
tags: 
   - cve.2025.53770
logsource:
   product: cma
detection:
   keywords:
       - '92bb4ddb98eeaf11fc15bb32e71d0a63256a0ed826a03ba293ce3a8bf057a514'        
       - '107.191.58.76'
       - '104.238.159.149'
       - '96.9.125.147'
       - 'Mozilla/5.0+(Windows+NT+10.0;+Win64;+x64;+rv:120.0)+Gecko/20100101+Firefox/120.0 /_layouts/SignOut.aspx'
       - '-EncodedCommand JABiAGEAcwBlADYANABTAHQAcgBpAG4AZwAgAD0'
       - 'TEMPLATE\LAYOUTS\spinstall0.aspx'        
       - '/_layouts/15/ToolPane.aspx DisplayMode=Edit'
       - '/_layouts/15/spinstall0.aspx'
       - 'spinstall'
       - 'yoserial'

   keywords_1:
       - 'POST'
       - 'GET'
   keywords_2:
       - '/_layouts/15/ToolPane.aspx'
   keywords_3:
       - 'DisplayMode=Edit'

   keywords_4:
       - 'POST'
       - 'GET'
       - 'curl'              
   keywords_5:
       - '/_layouts/'
       - 'layouts'  
   keywords_6:
       - 'ToolPane.aspx'
       - 'SignOut.aspx'
       - 'spinstall'
       - 'info3.aspx'

   keywords_7:
       - 'HTTP'
   keywords_8:
       - 'X-TXT-NET'

   keywords_9:
       - '.exe'
   keywords_10:
       - '-ap'
   keywords_11:
       - 'SharePoint'
   keywords_12:
       - '8080'
   keywords_13:
       - '.dll'
   keywords_14:
       - 'pipe'
   keywords_15:
       - 'inetpub'
   keywords_16:
       - 'config'

   keywords_17:
       - 'ysoserial'
   keywords_18:
       - 'ViewState'
   keywords_19:
       - 'TypeConfuseDelegate'
   keywords_20:
       - 'powershell'
   keywords_21:
       - '-EncodedCommand'

   keywords_22:
       - 'BiAGEAcwBlADYANABTAHQAcgBpAG4AZwAgAD0'
       - 'base64String='
   keywords_23:
       - 'BkAGUAYwBvAGQAZQBk'
       - 'decoded' 
   keywords_24:
       - 'BGAHIAbwBtAEIAYQBzAGUANgA0AFMAdAByAGkAbgBn'
       - 'FromBase64String'
   keywords_25:
       - 'cwBwAGkAbgBzAHQAYQBsAGwAMAAuAGEAcwBwAHg'
       - 'AuAGEAcwBwAHg'
       - 'spinstall0.aspx'
       - '.aspx'

   keywords_26:
       - 'V3JpdGUoY2cuVm'
   keywords_27:
       - 'bisifCIrY2cuRG'     
   keywords_28:
       - 'mFsaW'

   condition: keywords or keywords_1 and keywords_2 and keywords_3 or keywords_4 and keywords_5 and keywords_6 or keywords_7 and keywords_8 or keywords_9 and keywords_10 and keywords_11 and keywords_12 and keywords_13 and keywords_14 and keywords_15 and keywords_16 or keywords_17 and keywords_18 and keywords_19 and keywords_20 and keywords_21 or keywords_22 and keywords_23 and keywords_24 and keywords_25 or keywords_26 and keywords_27 and keywords_28

falsepositives:
   - Rate of FP moderate with some strings.
   - Use this rule in an infected environment/logs.
   - Analyst may need to make adjustments to the query as required.
level: critical

ssdeep Matches

No matches found.

Relationships

Description

This artifact is a data file containing the Base64 encoded .NET DLL "bjcloiyq.dll" (bee94b93c1...).

Screenshots

bee94b93c1796981a55d7bd27a32345a61304a88ed6cd70a5f7a402f1332df72

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_02 : steals_authentication_credentials exfiltrates_data
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250724_721"
         actor = "n/a"
         family = "n/a"
         capabilities = "steals-authentication-credentials exfiltrates-data"
         malware_type = "unknown"
         tool_type = "unknown"
         description = "Detects .Net DLL payload samples"
         sha256_1 = "bee94b93c1796981a55d7bd27a32345a61304a88ed6cd70a5f7a402f1332df72"
     strings:
         $s0 = { 62 6A 63 6C 6F 69 79 71 2E 64 6C 6C }
         $s1 = { 4D 61 63 68 69 6E 65 4B 65 79 53 65 63 74 69 6F 6E 00 54 79 70 65 }
         $s2 = { 67 65 74 5F 56 61 6C 69 64 61 74 69 6F 6E 4B 65 79 }
         $s3 = { 67 65 74 5F 43 75 72 72 65 6E 74 00 48 74 74 70 52 65 73 70 6F 6E 73 65 }
         $s4 = { 67 65 74 5F 44 65 63 72 79 70 74 69 6F 6E 4B 65 79 }
         $s5 = { 67 65 74 5F 44 65 63 72 79 70 74 69 6F 6E }
         $s6 = { 53 79 73 74 65 6D 2E 57 65 62 2E 43 6F 6E 66 69 67 75 72 61 74 69 6F 6E }
     condition:
         all of them
  }
   

SIGMA Rule

   ## CISA Code & Media Analysis ##

                           ############ README ###############
## Edit rules and queries as needed for your hunt and based on your environment.
## Ensure your EDR/SIEM instance has enough memory to run these AND/OR condition based queries. May take longer to run than conventional Sigma rule query. 
## Do not edit "logsource-product:" unless you are editing this rule to meet specific logsources/fields and know your environment.
## TLP GREEN + Please use local installation of Sigma to convert this rule.
## TLP CLEAR may convert rules using online converter of choice.
                           ###################################

title: Detects CVE-2025-53770 IOCs and Activity Based on Submitted Files 251132.r2
incident: 251133.r2
tlp: CLEAR
id: a9327942-4cf7-48e4-9ea4-ad0b54db4bf7 
status: test
description: Detects ToolShell CVE-2025-53770 Exploitation of SharePoint servers. Detects IOCs and Activity Based on Submitted Files 251132.r2.
references:
   - 251132.r2
author: CISA Code & Media Analysis
date: 2025-07-23
modified: 2025-07-23
tags: 
   - cve.2025.53770
logsource:
   product: cma
detection:
   keywords_1:
       - 'CVAUGFnZSBMYW5ndWFnZT0i'
       - '%@Page Language="'
   keywords_2:
       - 'Jwb3dlcnNoZWxsLmV4ZS'
       - 'powershell.exe'
   keywords_3:
       - 'ItZW5j'
       - '-enc'
       - 'LUVuY29kZWRDb21tYW5k'
       - '-EncodedCommand'
   keywords_4:
       - '0Jhc2U2NFN0cmluZy'
       - 'Base64String'
   keywords_5:
       - 'FJlcXVlc3QuRm9ybV'
       - 'Request.Form'
   keywords_6:
       - 'sicCJ'
       - '"p"'

   keywords_7:
       - '*.exe'
   keywords_8:
       - 'powershell*'
   keywords_9:
       - '-Command'
   keywords_10:
       - 'Get-ChildItem'
       - 'ForEach-Object' 
   keywords_11:
       - '*\TEMPLATE\LAYOUTS\*'

   keywords_12:
       - '*.exe'
   keywords_13:
       - 'certutil*'
   keywords_14:
       - '-decode'

   keywords_15:
       - 'c:\progra~1\common~1\micros~1\webser~1\16\template\layouts\owa\resources\*'
       - 'c:\progra~1\common~1\micros~1\webser~1\16\template\layouts\*'
       - '\template\layouts\*'
       - '\template\layouts\owa\*'
   keywords_16:
       - '*.aspx'
       - '*.txt'

   keywords_17:
       - '*\TEMPLATE\LAYOUTS\*'
   keywords_18:
       - 'spinstall*'
   keywords_19:
       - '*.aspx'

   condition: keywords_1 and keywords_2 and keywords_3 and keywords_4 and keywords_5 and keywords_6 or keywords_7 and keywords_8 and keywords_9 and keywords_10 and keywords_11 or keywords_12 and keywords_13 and keywords_14 or keywords_15 and keywords_16 or keywords_17 and keywords_18 and keywords_19

falsepositives:
   - Rate of FP low-moderate with some strings.
   - Use this rule in an infected environment/logs.
   - Analyst may need to make adjustments to the query as required.
level: critical

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Relationships

Description

This artifact is a 64-bit .NET DLL that contains a class named "E" (Figure 2) used to extract and concatenate machine key configuration settings within an ASP[.]NET application's configuration. The file uses reflection to access the "MachineKeySection" from the "System.Web" assembly, which contains cryptographic keys used for validation and decryption in ASP[.]NET. The file uses reflection to get and invoke the "GetApplicationConfig" method of the "MachineKeySection" class to retrieve the "machineKey" configuration, which holds the actual key values. The file constructs a string containing the "ValidationKey", "Validation", "DecryptionKey", "Decryption", and "CompatibilityMode" properties of the "machineKeySection" and adds it as a custom header named "X-TXT-NET" to the HTTP response.

Screenshots

3461da3a2ddcced4a00f87dcd7650af48f97998a3ac9ca649d7ef3b7332bd997

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_08 : steals_authentication_credentials exfiltrates_data
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250725_712"
         actor = "n/a"
         family = "n/a"
         capabilities = "steals-authentication-credentials exfiltrates-data"
         malware_type = "unknown"
         tool_type = "unknown"
         description = "Detects .Net DLL payload samples"
         sha256_1 = "3461da3a2ddcced4a00f87dcd7650af48f97998a3ac9ca649d7ef3b7332bd997"
     strings:
         $s0 = { 47 65 74 4C 6F 67 69 63 61 6C 44 72 69 76 65 73 }
         $s1 = { 67 65 74 5F 4D 61 63 68 69 6E 65 4E 61 6D 65 }
         $s2 = { 67 65 74 5F 53 79 73 74 65 6D 44 69 72 65 63 74 6F 72 79 }
         $s3 = { 67 65 74 5F 43 75 72 72 65 6E 74 44 69 72 65 63 74 6F 72 79 }
         $s4 = { 67 65 74 5F 50 72 6F 63 65 73 73 6F 72 43 6F 75 6E 74 }
         $s5 = { 67 65 74 5F 55 73 65 72 4E 61 6D 65 }
         $s6 = { 67 65 74 5F 4F 53 56 65 72 73 69 6F 6E }
         $s7 = { 45 6E 76 69 72 6F 6E 6D 65 6E 74 56 61 72 69 61 62 6C 65 73 }
         $s8 = { 53 79 73 74 65 6D 2E 57 65 62 2E 43 6F 6E 66 69 67 75 72 61 74 69 6F 6E }
         $s9 = { 4D 61 63 68 69 6E 65 4B 65 79 53 65 63 74 69 6F 6E }
         $s10 = { 67 65 74 5F 56 61 6C 69 64 61 74 69 6F 6E 4B 65 79 }
         $s11 = { 67 65 74 5F 44 65 63 72 79 70 74 69 6F 6E 4B 65 79 }
         $s12 = { 67 65 74 5F 44 65 63 72 79 70 74 69 6F 6E }
         $s13 = { 67 65 74 5F 43 6F 6D 70 61 74 69 62 69 6C 69 74 79 4D 6F 64 65 }
     condition:
         all of them
  }
   

SIGMA Rule

 ## CISA Code & Media Analysis ##

                           ############ README ###############
## Edit rules and queries as needed for your hunt and based on your environment.
## Ensure your EDR/SIEM instance has enough memory to run these AND/OR condition based queries. May take longer to run than conventional Sigma rule query. 
## Do not edit "logsource-product:" unless you are editing this rule to meet specific logsources/fields and know your environment.
## TLP GREEN + Please use local installation of Sigma to convert this rule.
## TLP CLEAR may convert rules using online converter of choice.
                           ###################################

title: Detects CVE-2025-53770 CVE-2025-53771 Updated IOCs and Activity 
incident: 251133.r2
tlp: CLEAR
id: 32bba1a1-3900-4cf9-b379-3e71a63998a3
status: test
description: Detects ToolShell CVE-2025-53770 Exploitation of SharePoint servers. Detects updated IOCs and Activity. CVE-2025-49704, CVE-2025-49706, CVE-2025-53770 and CVE-2025-53771. TA - Linen Typhoon, Violet Typhoon, Storm-2603.
references:
   - https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/?msockid=3e14885e8c2b643323129d998d366597
   - https://socradar.io/toolshell-sharepoint-zero-day-cve-2025-53770/
   - https://unit42.paloaltonetworks.com/microsoft-sharepoint-cve-2025-49704-cve-2025-49706-cve-2025-53770/
   - https://github.com/kaizensecurity/CVE-2025-53770/blob/master/payload
   - https://www.picussecurity.com/resource/blog/cve-2025-53770-critical-unauthenticated-rce-in-microsoft-sharepoint
   - https://www.trendmicro.com/en_us/research/25/g/cve-2025-53770-and-cve-2025-53771-sharepoint-attacks.html
author: CISA Code & Media Analysis
date: 2025-07-23
modified: 2025-07-23
tags: 
   - cve.2025.49704 
   - cve.2025.49706
   - cve.2025.53770
   - cve.2025.53771 
logsource:
   product: cma
detection:
   keywords:
       - '92bb4ddb98eeaf11fc15bb32e71d0a63256a0ed826a03ba293ce3a8bf057a514'
       - '4a02a72aedc3356d8cb38f01f0e0b9f26ddc5ccb7c0f04a561337cf24aa84030'
       - 'b39c14becb62aeb55df7fd55c814afbb0d659687d947d917512fe67973100b70'
       - 'fa3a74a6c015c801f5341c02be2cbdfb301c6ed60633d49fc0bc723617741af7'
       - '390665bdd93a656f48c463bb6c11a4d45b7d5444bdd1d1f7a5879b0f6f9aac7e'
       - '66af332ce5f93ce21d2fe408dffd49d4ae31e364d6802fff97d95ed593ff3082'
       - '7baf220eb89f2a216fcb2d0e9aa021b2a10324f0641caf8b7a9088e4e45bec95'
       - '8d3d3f3a17d233bc8562765e61f7314ca7a08130ac0fb153ffd091612920b0f2'
       - '30955794792a7ce045660bb1e1917eef36f1d5865891b8110bf982382b305b27'
       - 'b336f936be13b3d01a8544ea3906193608022b40c28dd8f1f281e361c9b64e93'

       - '107.191.58.76'
       - '104.238.159.149'
       - '96.9.125.147'
       - '103.186.30.186'
       - '45.77.155.170'
       - '139.144.199.41'
       - '172.174.82.132'
       - '89.46.223.88'  
       - '45.77.155.170'    
       - '154.223.19.106'   
       - '185.197.248.131'  
       - '149.40.50.15' 
       - '64.176.50.109'    
       - '149.28.124.70'   
       - '206.166.251.228'  
       - '95.179.158.42' 
       - '86.48.9.38'
       - '128.199.240.182'  
       - '212.125.27.102' 
       - '91.132.95.60'
       - '134.199.202.205'
       - '131.226.2.6'
       - '188.130.206.168'

       - 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:120.0) Gecko/20100101 Firefox/120.0'
       - 'Mozilla/5.0+(Windows+NT+10.0;+Win64;+x64;+rv:120.0)+Gecko/20100101+Firefox/120.0'
       - 'c34718cbb4c6.ngrok-free.app/file.ps1'

   keywords_1:
       - '*\TEMPLATE\LAYOUTS\*'
   keywords_2:
       - 'spinstall*'
       - 'debug*'
       - 'info*'
   keywords_3:
       - '*.aspx'
       - '*.js'

   keywords_4:
       - 'POST'
       - 'GET'
       - 'curl'
   keywords_5:
       - '*/_layouts/*'
       - '*/layouts/*'
       - '*layouts*'
   keywords_6:
       - '*ToolPane.aspx'
       - '*DisplayMode'
       - '*SignOut.aspx'
       - '*spinstall*'
       - 'VIEWSTATE'

   keywords_7:
       - 'cmd.exe'
   keywords_8:
       - 'powershell.exe' 
   keywords_9:
       - '-EncodedCommand'
       - '-ec'
       - '-enc'
       - 'VIEWSTATE'
       - 'yoserial*'

   keywords_10:
       - '*\TEMPLATE\LAYOUTS\*'
   keywords_11:
       - 'ChildItem'
   keywords_12:
       - 'targetFile'
   keywords_13:
       - 'NewLine'
   keywords_14:
       - '*web.config*'

   keywords_15:
       - 'Ry2cuVmFsaWRhd'
       - 'Validation'
   keywords_16:
       - 'ifCIRy2cuQ29tc'
       - 'Decryption'
   keywords_17:
       - 'dGlvb'
       - 'Key'
   keywords_18:
       - 'UZtleVNlY3Rpb2'
       - 'MachineKey'
   keywords_19:
       - 'ShudWxsLC'
       - 'Invoke'
   keywords_20:
       - 'XIiIGxhbmd1Y'
       - 'language'
   keywords_21:
       - 'qZWN0WzBdKTsNC'
       - 'new object'

   keywords_22:
       - 'POST'
       - 'powershell*'
       - '*layouts*'
   keywords_23:
       - 'ToolPane.aspx'
       - '*spinstall*'

   condition: keywords or keywords_1 and keywords_2 and keywords_3 or keywords_4 and keywords_5 and keywords_6 or keywords_7 and keywords_8 and keywords_9 or keywords_10 and keywords_11 and keywords_12 and keywords_13 and keywords_14 or keywords_15 and keywords_16 and keywords_17 and keywords_18 and keywords_19 and keywords_20 and keywords_21 or keywords_22 and keywords_23

falsepositives:
   - Rate of FP low-moderate with some strings.
   - Use this rule in an infected environment/logs.
   - Analyst may need to make adjustments to the query as required.
level: critical

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Description

This artifact is a 32-bit .NET DLL that contains a class named "E" (Figure 3) used to retrieve system and environment information, along with the machine key configuration settings (Figure 3). This class file is designed to iterate through and collect environment variables as well as retrieve and format .NET and system properties below: 

--Begin System Properties-- 
Number of logical drives 
Drive letters 
Computer name 
Full path of the system directory 
Current directory 
Processor count 
System uptime (milliseconds since start) 
Username 
Operating system version 
.NET version 
--End System Properties-- 

The file uses reflection to access the "MachineKeySection" from the "System.Web" assembly, which contains cryptographic keys used for validation and decryption in ASP[.]NET. The file uses reflection to invoke the "GetApplicationConfig" method of the "MachineKeySection" class to retrieve the "machineKey" configuration, which holds the actual key values. The file constructs a string containing the "ValidationKey", "Validation", "DecryptionKey", "Decryption", and "CompatibilityMode" properties of the "machineKeySection". The gathered information and the "MachineKeySection" details are formatted into a string before written to the HTTP response (current.Response object).

Screenshots

92bb4ddb98eeaf11fc15bb32e71d0a63256a0ed826a03ba293ce3a8bf057a514

Tags

webshell

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_03 : steals_authentication_credentials exfiltrates_data
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250724_721"
         actor = "n/a"
         family = "n/a"
         capabilities = "steals-authentication-credentials exfiltrates-data"
         malware_type = "unknown"
         tool_type = "unknown"
         description = "Detects aspx payload samples"
         sha256_1 = "92bb4ddb98eeaf11fc15bb32e71d0a63256a0ed826a03ba293ce3a8bf057a514"
     strings:
         $s0 = { 4C 6F 61 64 28 22 53 79 73 74 65 6D 2E 57 65 62 }
         $s1 = { 43 6F 6E 66 69 67 75 72 61 74 69 6F 6E 2E 4D 61 63 68 69 6E 65 4B 65 79 53 65 63 74 69 6F 6E }
         $s2 = { 52 65 73 70 6F 6E 73 65 2E 57 72 69 74 65 }
         $s3 = { 63 67 2E 56 61 6C 69 64 61 74 69 6F 6E 4B 65 79 2B 22 7C 22 }
         $s4 = { 2B 63 67 2E 56 61 6C 69 64 61 74 69 6F 6E 2B }
         $s5 = { 2B 63 67 2E 44 65 63 72 79 70 74 69 6F 6E 4B 65 79 2B }
         $s6 = { 2B 63 67 2E 44 65 63 72 79 70 74 69 6F 6E 2B }
         $s7 = { 2B 63 67 2E 43 6F 6D 70 61 74 69 62 69 6C 69 74 79 4D 6F 64 65 }
     condition:
         all of them
  }
   

SIGMA Rule

No associated rule.

ssdeep Matches

No matches found.

Description

This artifact is a malicious ASPX file used to retrieve and output machine key information from the "MachineKeySection" of the System[.]Web[.]Configuration namespace (Figure 4). This file uses reflection to dynamically load the "System.Web" assembly and access the "MachineKeySection" class within "System.Web.Configuration". The file invokes "GetApplicationConfig" to retrieve the "MachineKeySection" object and writes its properties including, ValidationKey, Validation, DecryptionKey, Decryption, and CompatibilityMode to the HTTP response using the "Response.Write()" method.

Screenshots

9340bf7378234db5bca0dc5378bf764b6a24bb87a42b05fa21a996340608fbd7

Tags

dropper

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_04 : dropper installs_other_components
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250724_721"
         actor = "n/a"
         family = "n/a"
         capabilities = "installs-other-components"
         malware_type = "dropper"
         tool_type = "unknown"
         description = "Detects Base64 encoded PowerShell dropper samples"
         sha256_1 = "9340bf7378234db5bca0dc5378bf764b6a24bb87a42b05fa21a996340608fbd7"
     strings:
         $s0 = { 63 6D 64 2E 65 78 65 5C 22 20 2F 63 20 70 6F 77 65 72 73 68 65 6C 6C 20 2D 43 6F 6D 6D 61 6E 64 }
         $s1 = { 46 72 6F 6D 42 61 73 65 36 34 53 74 72 69 6E 67 }
         $s2 = { 4F 75 74 2D 46 69 6C 65 20 2D 46 69 6C 65 50 61 74 68 }
         $s3 = { 69 6E 66 6F 33 2E 61 73 70 78 }
         $s4 = { 2D 45 6E 63 6F 64 69 6E 67 20 55 54 46 38 }
     condition:
         all of them
  }
   

SIGMA Rule

No associated rule.

ssdeep Matches

No matches found.

Relationships

Description

This artifact contains command-line instruction used to execute a PowerShell command (Figure 5). The PowerShell command decodes a Base64 encoded string into a Unicode Transformation Format-8 (UTF-8) string. The decoded content is then written to a file named "info3.aspx" (675a10e87c24....) located at c:\progra~1\\common~1\micros~1\webser~1\l16\template\layouts\. The output file is encoded using UTF8.

Screenshots

675a10e87c248d0f629da864ba8b7fd92b62323c406a69dec35a0e6e1552ecbc

Tags

webshell

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_05 : webshell exfiltrates_data fingerprints_host
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250724_721"
         actor = "n/a"
         family = "n/a"
         capabilities = "exfiltrates-data fingerprints-host"
         malware_type = "webshell"
         tool_type = "unknown"
         description = "Detects aspx webshell samples"
         sha256_1 = "675a10e87c248d0f629da864ba8b7fd92b62323c406a69dec35a0e6e1552ecbc"
     strings:
         $s0 = { 43 75 72 72 65 6E 74 2E 52 65 71 75 65 73 74 2E 46 6F 72 6D }
         $s1 = { 20 48 74 74 70 43 6F 6F 6B 69 65 20 6E 65 77 63 6F 6F 6B }
         $s2 = { 6E 65 77 63 6F 6F 6B 2E 45 78 70 69 72 65 73 20 }
         $s3 = { 52 65 73 70 6F 6E 73 65 2E 53 65 74 43 6F 6F 6B 69 65 28 6E 65 77 63 6F 6F 6B 29 }
         $s4 = { 43 6F 6D 70 75 74 65 48 61 73 68 }
         $s5 = { 44 26 46 72 69 32 6B 26 78 35 64 4D 49 53 54 6E 61 46 71 40 }
         $s6 = { 2A 68 75 5E 4D 23 6C 23 4C 72 6C 4E 6F 39 21 37 4B 4C 66 }
         $s7 = { 22 63 6D 22 20 2B 20 22 64 2E 65 22 20 2B 20 22 78 65 22 }
         $s8 = { 57 72 69 74 65 4C 69 6E 65 28 22 65 78 69 74 22 29 }
         $s9 = { 50 61 73 73 77 6F 72 64 }
         $s10 = { 43 6F 6D 6D 61 6E 64 }
         $s11 = { 55 70 6C 6F 61 64 }
         $s12 = { 74 79 70 65 3D 22 66 69 6C 65 22 }
         $s13 = { 74 79 70 65 3D 22 74 65 78 74 22 }
         
     condition:
         all of them
  }
   

SIGMA Rule

No associated rule.

ssdeep Matches

No matches found.

Relationships

Description

This artifact is a malicious ASP[.]NET web page (.aspx) that contains ASP[.]NET code embedded within an HTML structure. This file is a webshell installed by "info3.aspx" (9340bf73782....). The file handles various operations based on submitted form data or HTTP cookies. The file contains HTML code used to create forms. The forms allow the Threat Actor (TA) to enter a password and submit it using a "Login" button, enter a command into a text field, which can then be executed by clicking an "Execute" button, and upload files that includes two input fields: one for selecting a file (type="file") and another for text input (type="text") (Figure 7). 

The password form element is configured for POST method and the input field is named "nYOmkVTYH2". If the HTML form with a password is received from the TA via an HTTP POST request, the file checks if the submission form field parameter named "nYOmkVTYH2" is not null or empty. If the parameter is present and not empty, the file sets an HTTP Cookie named "wY1DC6wH4u" with a value from the form field "nYOmkVTYH2" and sets the HTTP Cookie expiration date to four days from the current time. This cookie is then added to the response. The file verifies if the HTTP cookie exists in the current HTTP request. If the cookie exists, its value is concatenated with a long hard-coded string "D&Fri2k&x5dMISTnaFq@ssyKk@rEM!98KzSKWpL4Nc8NvaA9AKdJVOtfdJ45FvbyYHxTql6kkc%qOZevc*hu^M#l#LrlNo9!7KLf". This combined string is then hashed using SHA512. The computed hash is converted to a Base64 string and compared against a predefined Base64 encoded string "9gYs0W/reXzR+KO6J/zP6naMU9AQwZCwhmXuPyGeY2VwMkxNGBZaJQAxGS6GvQZJLSAPk8LT0PgJVU1kQQJd2zW9w==" (Figure 6). This process determines whether a user or request is authorized. 

The command form element is configured for POST method and the input field is named "GTaRkhJ9wz". If the HTML form with a command is received from the TA via an HTTP POST request, the file checks if the submission form field parameter named "GTaRkhJ9wz" is not null or empty. If the parameter is present and not empty, the file creates a new process to execute a command-line utility "cmd.exe". The file redirects standard input, output, and error streams to capture the results of the executed command. The code writes the value of the "GTaRkhJ9wz" form parameter to the process's standard input, executing the value as a command, and then writes "exit" to terminate the process (Figure 6). 

The file upload form element is configured for POST method and "enctype"="multipart/form-data" to handle file uploads. It includes an input type="file" for selecting a file (input field named "0z3H8H8ato") and an input type="text" for providing a destination path or filename ( input field named "7KAjlfecWF"). If the HTML form for file upload is received from the TA, the file checks if the submission form field parameter named "7KAjlfecWF" (intended to be the file path or name) is not null or empty. The file retrieves the uploaded file through the "0z3H8H8atO" input using "HttpContext.Current[.]Request[.]Files["Oz3H8H8ato"]". If the file exists and has content (content length is greater than zero), the file saves the uploaded file using the path provided in the "7KAjlfecWF" field. Upon successful upload, the "InnerText" of an element named "Result" is set to "uploaded", indicating the file has been saved. If an error occurs during the process, the file captures the exception and displays its details in "Result.InnerText" (Figure 6). The file displays server-side generated output or messages to the TA.

Screenshots

d9c4dd5a8317d1d83b5cc3482e95602f721d58e3ba624d131a9472f927d33b00

Tags

webshell

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_06 : webshell fingerprints_host installs_other_components exfiltrates_data
  
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250725_712"
         actor = "n/a"
         family = "n/a"
         capabilities = "fingerprints-host installs-other-components exfiltrates-data"
         malware_type = "webshell"
         tool_type = "unknown"
         description = "Detects ASPX Webshell samples"
         sha256_1 = "d9c4dd5a8317d1d83b5cc3482e95602f721d58e3ba624d131a9472f927d33b00"
     strings:
         $s0 = { 3D 52 65 71 75 65 73 74 2E 46 6F 72 6D 5B 22 70 22 5D }
         $s1 = { 46 72 6F 6D 42 61 73 65 36 34 53 74 72 69 6E 67 28 65 6E 63 29 }
         $s2 = { 46 69 6C 65 4E 61 6D 65 3D 22 70 6F 77 65 72 73 68 65 6C 6C 2E 65 78 65 }
         $s3 = { 2D 45 6E 63 6F 64 65 64 43 6F 6D 6D 61 6E 64 }
         $s4 = { 2C 55 73 65 53 68 65 6C 6C 45 78 65 63 75 74 65 3D 66 61 6C 73 65 }
         $s5 = { 76 61 72 20 70 6C 3D 6E 65 77 20 62 79 74 65 }
         $s7 = { 36 38 39 30 31 61 33 39 34 61 37 36 64 63 35 30 36 34 66 62 61 39 36 62 38 36 }
         $s8 = { 32 36 36 35 65 65 35 39 36 62 31 61 31 34 36 38 62 64 63 36 }
         $s9 = { 31 38 31 35 37 64 37 63 63 61 30 31 33 30 39 30 32 65 }
     condition:
         all of them
  }
   

SIGMA Rule

No associated rule.

ssdeep Matches

No matches found.

Description

This artifact is a malicious ASPX file with a "Page_Load" event handler that constructs and executes a command using PowerShell on the server (Figure 8). Upon execution, the file takes a Base64-encoded string from a form parameter named "p". The Base64 encoded string is decoded and Exclusively-OR (XOR) decrypted using a hard-coded XOR key "68901a394a76dc5064fba96b862665ee596b1a1468bdc618157d7cca0130902e". The output of the XOR decrypted bytes are converted to a Unicode Transformation Format-8 (UTF-8) string and then Base64 encoded. The Base64 encoded string is passed as an argument to the PowerShell process "powershell.exe" using the "-EncodedCommand flag". The file redirects the standard output of the PowerShell process and reads it into a variable "o", which is then written back to the HTTP response.

Screenshots

d0c4d6a4be0a65f8ca89e828a3bc810572fff3b3978ff0552a8868c69f83d170

Tags

webshell

Details

Antivirus

No matches found.

YARA Rules

• rule CISA_251132_07 : webshell fingerprints_host installs_other_components exfiltrates_data
  {
     meta:
         author = "CISA Code & Media Analysis"
         incident = "251132"
         date = "2025-07-21"
         last_modified = "20250725_712"
         actor = "n/a"
         family = "n/a"
         capabilities = "fingerprints-host installs-other-components exfiltrates-data"
         malware_type = "webshell"
         tool_type = "unknown"
         description = "Detects ASPX Webshell samples"
         sha256_1 = "d0c4d6a4be0a65f8ca89e828a3bc810572fff3b3978ff0552a8868c69f83d170"
     strings:
         $s0 = { 61 38 35 39 66 30 32 30 38 37 37 37 34 36 32 38 39 39 64 66 36 37 62 33 64 38 31 61 37 62 38 62 }
         $s1 = { 70 6F 77 65 72 73 68 65 6C 6C 2E 65 78 65 }
         $s2 = { 41 72 67 75 6D 65 6E 74 73 3D 22 2D 65 6E 63 20 22 }
         $s3 = { 52 65 71 75 65 73 74 2E 46 6F 72 6D 5B 22 70 22 5D }
         $s4 = { 55 73 65 53 68 65 6C 6C 45 78 65 63 75 74 65 3D 66 61 6C 73 65 }
         $s5 = { 52 65 64 69 72 65 63 74 53 74 61 6E 64 61 72 64 4F 75 74 70 75 74 3D 74 72 75 65 }
         $s6 = { 53 74 61 6E 64 61 72 64 4F 75 74 70 75 74 }
         $s7 = { 52 65 73 70 6F 6E 73 65 2E 57 72 69 74 65 }
         $s8 = { 47 65 74 42 79 74 65 73 28 6F 29 }
     condition:
         all of them
  }
   

SIGMA Rule

No associated rule.

ssdeep Matches

No matches found.

Description

This artifact is a malicious ASPX file with a "Page_Load" event handler that constructs and executes a command using PowerShell on the server (Figure 9). Upon execution, the file constructs a PowerShell command that decodes a Base64 string from the request form parameter "p". The decoded string is decrypted using the XOR function with the hard-coded key "a859f0208777462899df67b3d81a7b8b". The decrypted bytes (command) is executed using a PowerShell command. The standard output of the executed PowerShell command is converted to a UTF-8 string, then encrypted using the XOR function with the same hard-coded key. The encrypted bytes data is Base64 encoded before written to the HTTP response using "Response.Write".

Screenshots

CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of their organization's systems. Any configuration changes should be reviewed by system owners and administrators prior to implementation to avoid unwanted impacts.

• Maintain up-to-date antivirus signatures and engines.
• Keep operating system patches up-to-date.
• Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory authentication.
• Restrict users' ability (permissions) to install and run unwanted software applications. Do not add users to the local administrators group unless required.
• Enforce a strong password policy and implement regular password changes.
• Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be known.
• Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests.
• Disable unnecessary services on agency workstations and servers.
• Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its "true file type" (i.e., the extension matches the file header).
• Monitor users' web browsing habits; restrict access to sites with unfavorable content.
• Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.).
• Scan all software downloaded from the Internet prior to executing.
• Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs).

Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology (NIST) Special Publication 800-83, "Guide to Malware Incident Prevention & Handling for Desktops and Laptops".

• 1-888-282-0870
• CISA Service Desk (UNCLASS)
• CISA SIPR (SIPRNET)
• CISA IC (JWICS)

CISA continuously strives to improve its products and services. You can help by answering a very short series of questions about this product at the following URL: https://www.cisa.gov/forms/feedback

What is a MIFR? A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis in a timely manner. In most instances this report will provide initial indicators for computer and network defense. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

What is a MAR? A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware analysis acquired via manual reverse engineering. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

Can I edit this document? This document is not to be edited in any way by recipients. All comments or questions related to this document should be directed to the CISA at 1-888-282-0870 or CISA Service Desk.

Can I submit malware to CISA? Malware samples can be submitted via the methods below:

• Web: https://www.cisa.gov/resources-tools/services/malware-next-generation-analysis
• For larger files (over 100MB), please reach out to CISA for instructions.

CISA encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, software vulnerabilities, and phishing-related scams. Reporting forms can be found on CISA's homepage at www.cisa.gov.