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

Static analysis result for SHA-256 a2c8c0c0fda4d924…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:34:06 Authoring application: Microsoft Excel
MD5: 39f9323537935f123b834a258ff59c70 SHA-1: 3eaa026884f487d2e7fbc12c64ef81a11e20adf1 SHA-256: a2c8c0c0fda4d9246ba9e8a3f8c60b554405e1d0ec41cdf2eff3247b09d9f11c
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates the macro is designed to execute arbitrary commands. This strongly suggests the file's purpose is to download and execute a secondary payload, a common technique for initial access.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a42fe01d1b682bfee90dd9cd5318fbccfb3504bc34e6d9620a757a138e1712ab		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6493 bytes

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