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

Static analysis result for SHA-256 8e466b13ecaf9c77…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:41:01 Authoring application: Microsoft Excel
MD5: 5ae9c9ffceb256822f4aefb76fac44dd SHA-1: e2d8e77840bd0296a3346deb9207f60c31a39588 SHA-256: 8e466b13ecaf9c77fe340e049e5978ea7480f75736d8f89f098e22573af5f81c
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel 4.0 macro-enabled spreadsheet. Static analysis detected an Auto_Open defined name, which is a critical indicator of malicious intent. This function is designed to execute arbitrary commands upon opening the workbook, likely for downloading and executing a second-stage payload. The extensive obfuscated data in the document body suggests an attempt to hide malicious content.

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
6afea3a2767521705bcb3ecddf06940e22525e3876443a573208c9bc1dbffeae		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6631 bytes

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