Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 6d07d75be0961578…

MALICIOUS

Office (OOXML)

17.7 KB Created: 2021-06-25 09:12:00 UTC Authoring application: Microsoft Office Word 12.0000 First seen: 2021-07-07
MD5: 08a6ba0daf3ee23a055c9fec10932cc7 SHA-1: 59c84d94fdef7105a940e31b4f7011d4255b2222 SHA-256: 6d07d75be09615780929d546e5ca4d7ab298345ce518de3026b5f3bae0cec9e9
362 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The sample is an OOXML document containing VBA macros. The presence of AutoOpen, Auto_Open, and Workbook_Open macros, along with a critical heuristic firing for Shell() call in VBA, indicates that the document is designed to execute arbitrary code upon opening. The script explicitly calls 'calc.exe' via the Shell function, which is a common technique to test execution capabilities before downloading a more malicious payload. The ClamAV detection further confirms its malicious nature as a downloader.

Heuristics 8

  • ClamAV: Doc.Downloader.Generic-6698421-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Generic-6698421-0
  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_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.
  • 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.openxmlformats.org/markup-compatibility/2006 In 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.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/2006/wordmlIn 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) 824 bytes
SHA-256: 04e12bba9c5f6a46f7b9fd8596b1a126690cb9b54a8abd90e96651c32e50f972
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "0{00020906-0000-0000-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 = "NewMacros"
Sub Auto_Open()
MsgBox (MsgBox(Shell("calc.exe")))
End Sub
Sub AutoOpen()
Auto_Open
End Sub
Sub Workbook_Open()
Auto_Open
End Sub


Attribute VB_Name = "UserForm1"
Attribute VB_Base = "0{95311432-C4E2-4DF2-A83B-7439ADCCA376}{5DBDC2AE-8540-4CF1-94EE-749E3945A4EC}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 18432 bytes
SHA-256: 8c75dcf830eb185857a9b29ce69f33c09e467132f8fc94b93a3a3b1fc1efd876
Detection
ClamAV: Doc.Downloader.Generic-6698421-0
Obfuscation or payload: unlikely

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