Office (OOXML) / .XLSX malware analysis — malicious · 506e808afde5120d

MALICIOUS

Office (OOXML) / .XLSX

96.1 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-11-07

MD5: 486dc0d8a1cc4af230c8774944d58821 SHA-1: f473a5b98be9dcd08166d9a968fb57077466b06f SHA-256: 506e808afde5120dd33f4ac510a45cf7a0f640809b659c46542eee1da721396c

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, the presence of a path string resembling 'C:\ProgramData\Microsoft\Excel.rtf' suggests the macro's intent is to download and execute a second-stage payload, likely disguised as a rich text file. This points to a common macro-based malware delivery technique.

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` `128fc99fecbf3162e028c561bea631af207e941ae5f131bc90a97baf3cd64b79`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	286860 bytes

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