Office (OOXML) / .XLSX malware analysis — malicious · bcd3ab61bc6675ec

MALICIOUS

Office (OOXML) / .XLSX

58.0 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: daeb05b94a1ac1abc6afe6e485ad7414 SHA-1: 1936abb1cfe91e5354997f411e89aafe8ae805ff SHA-256: bcd3ab61bc6675ecd97e5f599a960555a7cc658a8d643d6e9df97247c1bf1f14

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. The macro sheet appears to contain obfuscated commands, including a path that resembles a directory for dropped files or executables. The macro's intent is likely to download and execute a second-stage payload from this location.

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` `88a9dca16c73302447e49ae066e8e8b7285258ea5fef0a58b21a1d0933c5c644`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4632 bytes

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