Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 86a46d277a4b7790…

MALICIOUS

Office (OOXML)

12.2 KB Authoring application: Microsoft Excel 16.0300 First seen: 2021-11-23
MD5: 8de76b61a869906213003d2bfc6a7f4a SHA-1: 5bf10bf83f3e31f83e3c842a78e480074d9c8a45 SHA-256: 86a46d277a4b779014cdb2c5f1f45610828fdc9715c435b4a597af9e296aa155
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

This OOXML document contains a Workbook_Open VBA macro that utilizes the Shell() function to execute 'calc.exe'. This indicates an attempt to run arbitrary code, likely as a precursor to downloading and executing a more malicious payload. The presence of a Workbook_Open macro and a Shell() call are strong indicators of malicious intent.

Heuristics 4

  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open 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.

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) 858 bytes
SHA-256: 34d334a9e5fdcc6114392302944f72ba2bcc5b40e8f45e7dd45c11aea5a30f0d
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 = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Sub Workbook_Open()
    Dim Program As String
    Dim TaskID As Double
    On Error Resume Next
    Program = "calc.exe"
    TaskID = Shell(Program, 1)
    If Err <> 0 Then
        MsgBox "Can't start " & Program
    End If
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 = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 12800 bytes
SHA-256: c030647d08e45c5f4128878cb361a86d03ad7bd6ce582c6e1ec815d981c2964d

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