Office (OLE) / .XLSX malware analysis — malicious · 4180266ea13f7b10

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:44:02 Authoring application: Microsoft Excel

MD5: d2d66c310280b0cb9cb12b0bea197e06 SHA-1: 2ce68254413259ee50202487bdde67eaecb6cdb1 SHA-256: 4180266ea13f7b10133cde05ca0156cf6cf37b3d8362d888a79a431d85e82e74

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The file is an Excel 4.0 macro-enabled workbook. Heuristics indicate the presence of an Auto_Open defined name, which is a critical indicator of malicious intent. This function is used to execute arbitrary commands, likely to download and run a second-stage payload. The extensive obfuscated data in the document body suggests attempts to hide malicious content or evade detection.

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` `8eccc4912995ca013ddc9a8e3163651893076f6c06bb0cedd5099ca4e69c8200`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6639 bytes

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