Office (OLE) / .XLSX malware analysis — malicious · 346566a4153a1a31

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:45:29 Authoring application: Microsoft Excel First seen: 2023-03-30

MD5: cddadcb2f1e8be946577e547d4b2f511 SHA-1: f9db1e42a3a3e35076a371de508136ed167f6ee1 SHA-256: 346566a4153a1a31a509ebec84a81e0b1659353771ef48801ae6b86afd895da3

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1059.001 PowerShell

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro. This macro is designed to execute automatically when the workbook is opened, which is a common technique for delivering malicious payloads. The heuristic OLE_XLM_DANGEROUS_FN further confirms the use of dangerous functions within the macro, increasing the likelihood 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` `8c16d188689e98b00dbefba08149d412972293fd87157c509e193c29ace26768`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6603 bytes

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