Office (OLE) / .XLSX malware analysis — malicious · 0a5e4c7b78e6f881

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:46:35 Authoring application: Microsoft Excel

MD5: 652d2aef26293256d0908444cc926e83 SHA-1: cfe1aa91c272008cc2fdf6b4ecf02ec6ccde7452 SHA-256: 0a5e4c7b78e6f881ac42f4a7aaf16605d36582eec3f5815df53772b354e16caa

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristic firings. The presence of an Auto_Open entry suggests that the macro will execute automatically when the workbook is opened. The dangerous formula API 'RUN' was also detected, which is commonly used to download and execute additional malicious content. No specific family could be identified.

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` `538dff51bc973204f6449f2059a882eb64a0dcf786e45472a25f756845b800fb`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6830 bytes

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