Office (OLE) / .XLSX malware analysis — malicious · 48c106d10e9e3041

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:47:40 Authoring application: Microsoft Excel

MD5: e9938475709d8312f17405efb481bbee SHA-1: 5ff88d2315dbc794658bdeaa387d4ab90ecfd8db SHA-256: 48c106d10e9e304108b3e3d017563cabf45c966698bd191811fc01da8a7c3cc7

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands. While the specific commands are not fully visible due to truncation, the pattern strongly indicates a downloader or initial execution stage for further malicious activity.

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` `6c08e03c1968eb0eb838e1b0d6b135da3f1c0e291451250f647268feed8509e3`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6833 bytes

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