Office (OLE) / .XLS malware analysis — malicious · 211dafb1508c0dd5

MALICIOUS

Office (OLE) / .XLS

57.5 KB Created: 2021-03-09 11:31:15 Authoring application: Microsoft Excel

MD5: 008a38a3ae5a52bff9ac3be0357619c8 SHA-1: d6ecd65769eb8ff1dbf7cfd80d3dee53dfc43e32 SHA-256: 211dafb1508c0dd5af66552f5cc705aaf337ca4cf5b0220342df326702098918

80 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open macro, which is a known technique for executing malicious code when the spreadsheet is opened. The macro sheet contains obfuscated function calls and string concatenations that are indicative of a downloader or initial execution stage. The presence of the Auto_Open defined name strongly suggests an attempt to automatically run code.

Heuristics 2

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.
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` `5aa50d81c4fa58f5af1e30b2dc521035089806aa3cce74fea53d20b2b37c69ec`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	55150 bytes

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