Office (OLE) / .XLSX malware analysis — malicious · 8bc7f07c4c24f1d1

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:32:24 Authoring application: Microsoft Excel

MD5: 5ee4464421f7a677642de833535e666d SHA-1: 423fb8e3dbfc0ca71771a9b2702d7ebf312376f8 SHA-256: 8bc7f07c4c24f1d1ab6bfdb9b70b68077e6be36198ca11a6dba896bb5462e53f

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open function, 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. This points to a macro-based attack pattern aimed at delivering a secondary payload. No specific family could be identified.

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` `d02b4642fc148396ae7337ae36d52ab4ff160f368d9c37388087399c736b4572`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6634 bytes

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