Office (OOXML) / .XLSX malware analysis — malicious · 5105f629084a6018

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: f5845dacda5a3648470655a32b46eacc SHA-1: 0a8a536408aa0ab392ac9e01061c74179b18da92 SHA-256: 5105f629084a6018f9e4435205e7b7271e1e4287e2dea057b62da6c720580e1e

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic 'OOXML_XLM_MACROSHEET' indicates the presence of an Excel 4.0 macro sheet. The extracted macro content, though partially obfuscated, suggests an attempt to execute commands, specifically referencing 'C:\ProgramData\excel.rtf', which is likely a path for a downloaded payload. This points to a macro-based execution attack pattern.

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` `acadc5c9468ff6479830da4ef7a77693b34433ba1110ae647deda7786a517d63`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	186174 bytes

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