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

Static analysis result for SHA-256 3478454a67ff69c8…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:44:09 Authoring application: Microsoft Excel
MD5: 19abc28ac0e61273e92e48b547ece90e SHA-1: 7e4efd9d864eb553f0b9debddb65c950c641c2de SHA-256: 3478454a67ff69c838f4c312580c015f4ecaf48c330372cb7b775754f4036e2f
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open defined name, which is a critical indicator of malicious intent. This function is designed to automatically execute when the workbook is opened, likely to run arbitrary commands. The specific dangerous formula APIs used, such as RUN, further confirm the malicious nature of the macro. No specific IOCs like URLs or hashes were extracted, but the Auto_Open function itself is the primary IOC.

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
a85f7503d5fb32b3dd9aa39498e3a423737a37b3c422ad007db1a64cfb9200be
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6664 bytes