Office (OLE) / .XLSX malware analysis — malicious · a230a6a674d556d3

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-27 11:44:13 Authoring application: Microsoft Excel

MD5: 4f691604ffae7c1cf18605b105057d97 SHA-1: 5e1636223aa2368a2ee9905ff065da2853daea0b SHA-256: a230a6a674d556d3f1f84612ceea77b4a68eff65878dd645ebf2ce5825e96912

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. This strongly suggests the file is a downloader or dropper, intended to fetch and execute further malicious content. No specific IOCs were extracted, but the technique is clear.

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` `36aa34201c187121b6989a2e85bc8e6a0e9e9d59cf02bf5022d7f371c575f777`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6571 bytes

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