Office (OOXML) / .XLSX malware analysis — malicious · 3e08a05c04ed3a49

MALICIOUS

Office (OOXML) / .XLSX

59.1 KB Created: 2021-03-15 18:25:06 UTC Authoring application: Microsoft Excel 16.0300

MD5: 39bc788a3b732b5b5de56db2e83d3290 SHA-1: 49155f32b635defa8f1fbad9f741e959152da55c SHA-256: 3e08a05c04ed3a493393bbc3e462fc964eafc42d97bb1072149a001ea559327b

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file identified as containing Excel 4.0 macros. The heuristic firing indicates the presence of these macros, which are often used to execute arbitrary commands or download further payloads. The macro content is heavily truncated and obfuscated, preventing a detailed analysis of its specific actions or the reconstruction of any URLs or commands.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `fd0eb65b80a2c64c13c3d5f3ca44a91de37245895a0d5377688e1104ae794b6f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	94320 bytes

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