Office (OOXML) / .XLSX malware analysis — malicious · bb2350ec11c8b5f1

MALICIOUS

Office (OOXML) / .XLSX

70.8 KB Created: 2021-03-14 19:50:37 UTC Authoring application: Microsoft Excel 16.0300

MD5: ed33e859df095416f8e2e0a330c6cc60 SHA-1: 471db1230bbc1a063796eb1c6c4cde4ea051d9a7 SHA-256: bb2350ec11c8b5f1778ed935c012b7453f3dc8f7ae0908bdd8fd6397f55feb92

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macrosheet content is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions. However, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands, typically for downloading and running a secondary payload. Without further deobfuscation or script content, the exact family cannot be determined.

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` `b2408d0b6c593d5edd3aaf5ea23f0796ace10bfc1a0a7658009a14a543f61ffe`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	97004 bytes

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