Office (OLE) / .XLSX malware analysis — malicious · 759c477dee75d578

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:32 Authoring application: Microsoft Excel

MD5: 604618eecc0f1b9b50e4367a558f2b9a SHA-1: 7f1a437517310392458c30b4d87531653ff5227b SHA-256: 759c477dee75d578c31dcbecbe376062bb4a7e7932032b37fa263e58f7b8d9ee

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

This Excel file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a known method for executing malicious code. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. The macro sheet itself is heavily obfuscated, suggesting an attempt to hide its malicious functionality.

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` `562e782a7ca24f447651b887e4fe1fd705a012699112defd30c87fdc4a01c0d8`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6473 bytes

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