Office (OLE) / .XLSX malware analysis — malicious · 5b41fe75a4eb478e

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:40:07 Authoring application: Microsoft Excel

MD5: 9fdbb022af8eb25c684715f11b8722e9 SHA-1: b484eeab1850f47a502fb0b454f43897e3f853cf SHA-256: 5b41fe75a4eb478eca9313f9c6644b6ad0788bc7701273cb3a51a9c31f33f3db

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution upon opening. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands, likely leading to further malicious activity. No specific family could be identified, but the technique is common for initial execution.

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` `8a535829475fe45152a41fc92f1025c3c8add5ebf5e5287aa454eb3cf74dbd7e`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6981 bytes

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