Office (OLE) / .XLSX malware analysis — malicious · e500d8959668e1ed

MALICIOUS

Office (OLE) / .XLSX

43.5 KB Created: 2020-10-14 08:50:46 Authoring application: Microsoft Excel

MD5: 0aaee40d3bc23fa0893b0e264adad8f9 SHA-1: bd3d10d6afe79ba4642fd57331e54b79402d504e SHA-256: e500d8959668e1ed83aa9bf7a615762b3ec318f69e56c6d2b4d598fb6227f6ed

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1569.002 ShellExecute

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open defined name, which is a critical finding. The heuristics indicate the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. While no specific URLs or hashes were extracted, the presence of the Auto_Open function strongly implies an intent to download and execute a secondary payload.

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.

Filename	Kind	Source	Size
`xlm_macros.txt` `b5028b36f920d22a0b9819fcb90742fcc49140ca55cf86a85f4134295e8338f0`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	9080 bytes

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