Office (OOXML) / .XLSX malware analysis — malicious · efb42b3b350b84fc

MALICIOUS

Office (OOXML) / .XLSX

138.4 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: f2e0730d139f1678ea684c64e19bcb4b SHA-1: 536424c97f9dabe59260da33a56c36b733235e93 SHA-256: efb42b3b350b84fc4f0818710d613fdaecddf6b000420543e172f42fa40d9003

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. While the macro content is truncated and heavily obfuscated, the presence of such macros strongly suggests an intent to download and execute a secondary payload. The file's metadata shows it was authored by Microsoft Excel.

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` `ab43fa165d2e8480fda21ffd0b1d15c013797b2aa35311591d7b7bb38e9fca13`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	644244 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.