Office (OLE) / .XLSX malware analysis — malicious · 1e19ca539298570b

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:41:53 Authoring application: Microsoft Excel

MD5: 070c45ba6fc35f7ff5706c51ffaa4a2e SHA-1: 4cef0aa75730c41963f841f2758b2377272cb35b SHA-256: 1e19ca539298570b992702cc1e81d1a42d1f6968e039a2eb4641e3a30d21f6df

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates that the workbook is configured to automatically execute a macro when opened. The presence of dangerous formula APIs, including the RUN function, suggests that the macro is capable of executing arbitrary commands. No specific malware family was identified, but the technique is commonly used for initial execution and payload delivery.

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` `8bd62aeea03e45d8b0c73ae7f8d8f08c1c856b0720f1e5ecbb1779b449939058`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6829 bytes

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