Office (OLE) malware analysis — malicious · 40ff34663747af12

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:34:01 Authoring application: Microsoft Excel

MD5: f9d625d39d11c4508ce5306c419e0cc7 SHA-1: 7c41c8e377142d9e7d1a1e14e172faea65175e23 SHA-256: 40ff34663747af1284e5407f28c37c15979433c2873ed35c85fe5f90f8a4fc02

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is an Excel document containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_AUTOOPEN_DEFINEDNAME heuristics. The critical OLE_XLM_DANGEROUS_FN heuristic specifically flags the use of dangerous formula APIs like RUN within the Auto_Open macro, suggesting it's designed to execute arbitrary code. This is a common technique for delivering secondary payloads, hence the likely attack pattern.

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` `491f771fd789bb730d1d1b7d02386a0e7a083c4dc31c8f79ca89d68fe28d2a33`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6500 bytes

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