Office (OLE) / .XLS malware analysis — malicious · 2c861f99439d5034

MALICIOUS

Office (OLE) / .XLS

31.5 KB Created: 2021-01-20 13:23:13 Authoring application: Microsoft Excel

MD5: 40c4be0a32ba7510bbd07dd68d501c7b SHA-1: 85fb9debaf5cd3b3e528f2273c134c8d71033172 SHA-256: 2c861f99439d5034c0540e35265db8bae026ad0e670558c006f17f064c680f31

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code. The macro sheet contains references to dangerous functions like RUN, suggesting it is designed to execute arbitrary commands. No specific IOCs were extracted, but the presence of the Auto_Open macro is a strong indicator of malicious intent.

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` `89a4201a26226262da5aa16dec89bee822990313bf03bdfb18f53f52d9ee7d3a`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3466 bytes

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