Office (OLE) / .XLSX malware analysis — malicious · 2e214d4becf5ba70

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:39:44 Authoring application: Microsoft Excel

MD5: 0a6c1814570c3f8b0442ce8e6b7b9e3b SHA-1: 223e72b18a0722cb164bb21af6b73a51fa358bb1 SHA-256: 2e214d4becf5ba7092a8c6731132c1e1f74c84bd3d2d797edbd4cf983f71c033

140 Risk Score

Malware Insights

MITRE ATT&CK

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

The file is an Excel spreadsheet containing Excel 4.0 (XLM) macros. Critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for automatically executing malicious code upon opening the document. The macro sheet itself contains a large amount of obfuscated data, suggesting it is designed to perform a malicious action, likely command execution via the RUN function.

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` `1165b3b2984b46c8de8c2d5ab6cc109360542a94823509955b5af274b23f168c`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6651 bytes

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