Office (OLE) / .XLSX malware analysis — malicious · 3d7606f59b60d4c7

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:45:33 Authoring application: Microsoft Excel

MD5: 40b0ab304b8618c5834b73b3889a4f7a SHA-1: d445fd86797dca26cca361dfcaf464451560eef7 SHA-256: 3d7606f59b60d4c70943869cfb6e9523b209cf02f7dbdd6a533e1036d17b8cd7

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open defined name. This indicates the file is designed to automatically execute code upon opening. The heuristics indicate the use of dangerous formula APIs, specifically the RUN function, which is used to execute arbitrary commands. The document body contains obfuscated strings that are likely part of the macro's payload or execution logic.

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` `30f75a093f2c5febd92f4d5284bd32b0e4c3e331ddd3a221cdca8b13fb139050`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6618 bytes

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