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

Static analysis result for SHA-256 49121f6dff8efcd1…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:42:11 Authoring application: Microsoft Excel
MD5: 3c46352871d8f44d353edcc174187e2a SHA-1: 33a10bb53ae85fac600812f20a60fcf38dcf23c8 SHA-256: 49121f6dff8efcd1948d5e7d92f1889092e295ded9958ada528ce4898e4692b1
140 Risk Score

Malware Insights

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

The file is an Excel spreadsheet containing Excel 4.0 macros. Critical heuristics indicate the presence of an Auto_Open defined name and the use of dangerous formula APIs, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands upon opening the document. No specific URLs or hashes were extracted, but the presence of Auto_Open with the RUN function strongly implies a downloader or initial execution stage.

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
a00e8b01d084601f70e6bbab2a18e15cce6bad00c8ca9b296465cad34906b7f2
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6650 bytes