Office (OLE) / .XLSX malware analysis — malicious · e04a94f826f99db3

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:31:42 Authoring application: Microsoft Excel

MD5: d412021169b902dc2ca3492e1446f7f2 SHA-1: 9d00b42a5cfb6c5832c9ba101272369519a2afbc SHA-256: e04a94f826f99db3eb437bf850dfddd5029445c846bed8659e4b0f8e2704bbcd

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel file containing Excel 4.0 (XLM) macros. Critical heuristics indicate the presence of an Auto_Open defined name and the use of dangerous formula APIs, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands upon opening the workbook. No specific IOCs like URLs or hashes were extracted, but the presence of the Auto_Open function 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` `1029652022ffc00fdd4f15d3d07063559cdc493fac13f7c98b68b870e77c53e1`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6656 bytes

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