Office (OOXML) / .XLSX malware analysis — malicious · 115e3c2177c76253

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: a5a3f1dfc67910d8afe518b74f8ee835 SHA-1: c1f1766f5c4d3f4edc330e92e1313e851ee3c32b SHA-256: 115e3c2177c76253b064e00119b5f0fc94113ed7a8887d2b4726144fb264c564

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. These macros are capable of executing arbitrary commands, which is a common technique for downloading and executing further malicious content. No specific family could be identified due to the obfuscated nature of the macro content.

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` `c12ff10d7d3574dab51b606336f09593017471fd867693518ca7251c38020cc5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7146 bytes

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