Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 81e9775d7caff4e5…

MALICIOUS

Office (OLE) / .XLSX

1.82 MB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel First seen: 2023-02-06
MD5: 97f9fd3a561207432acb18ba84544a7d SHA-1: 304a952fe1f0fa8d90c3edbe5fdf563e6ba32ae6 SHA-256: 81e9775d7caff4e54b6ddc20c5183351707a8c10623c6014c34960315f039d5e
528 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1087.001 Local Accounts T1059.003 Windows Command Shell

This XLSX file contains Excel 4.0 macros and VBA code, including Workbook_Open and Auto_Open events, indicating an attempt to automatically execute malicious actions upon opening. The presence of Shell() calls and WScript.Shell usage strongly suggests the macro is designed to download and execute a secondary payload. The ClamAV detection name 'Xls.Virus.Mailcab-6702020-0' further supports its malicious nature.

Heuristics 13

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • VBA WMI Win32_Process launcher critical OLE_VBA_WMI_PROCESS_CREATE
    VBA macro builds or references a WMI moniker for Win32_Process and invokes .Create to start a command. This is a high-confidence macro execution chain that often hides the WMI class name through string concatenation or helper functions.
  • ClamAV: Xls.Virus.Mailcab-6702020-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Virus.Mailcab-6702020-0
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • 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.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
fa0838c1245cc5ee082d163c6113481a62410d6c1b500ccab49b8f78fd5b088b		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 27130 bytes

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