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

Static analysis result for SHA-256 59521f4d17e62cb9…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:39:11 Authoring application: Microsoft Excel
MD5: f6bedc1c6c72443745c6287f5192ef62 SHA-1: 7a981150f9667a3a988c7f0f8ca48010406f86dc SHA-256: 59521f4d17e62cb9e35a295aaa68affec74b227968fbc77c385e29be1664cbd8
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open function, which is a critical indicator of malicious intent. This function is designed to automatically execute when the workbook is opened, allowing for the execution of dangerous formula APIs like RUN. The presence of an Auto_Open entry strongly suggests the file is intended to deliver a malicious payload upon opening.

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
7f54ce27452037e49c0bcd0b82ad4d1267f7ef83f206027fe8b60f93c8a9ba56		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6496 bytes

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