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

Static analysis result for SHA-256 4e41e5eb594e8cce…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:42:08 Authoring application: Microsoft Excel
MD5: 561e3c80d86612d4d203004e9d5fd78b SHA-1: a774528d3be23b19474b75368f87bd72e1b19b46 SHA-256: 4e41e5eb594e8ccec55e6c817276f8b097c2d8cdf1876c00ac1ba8ac60db98f0
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications

The file contains Excel 4.0 macro sheets with an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates an intent to execute arbitrary code. While the specific payload is not clear from the provided data, the mechanism strongly suggests a malicious downloader or dropper.

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
ca7f6aa0b34553e1e7c709af7c51ddef4abb0a51b6c1e736af70a2698bc7343c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6658 bytes

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