Office (OLE) / .XLSX malware analysis — malicious · 1f2fe4ad0bb5b390

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:43:12 Authoring application: Microsoft Excel

MD5: 5c3b59239b52d812715d2a5b84500db5 SHA-1: 114c1bd065efa1e7e3c0508e0b367065df21a4a1 SHA-256: 1f2fe4ad0bb5b3905de2b53d84d89ebfbc905b98c943427bba5fbe259c0a9c80

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like 'RUN' indicates that the macro is designed to execute arbitrary commands. While the exact payload is not discernible from the provided evidence, the Auto_Open function strongly suggests an attempt to immediately execute malicious code upon opening the spreadsheet.

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` `ddf10ac06a618d5296dad01e41b4463a521252739eaf450848595d65a2d4da0e`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6700 bytes

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