Office (OOXML) / .XLSX malware analysis — malicious · d8c12fb3fc8f75b9

MALICIOUS

Office (OOXML) / .XLSX

62.9 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300

MD5: 7a915d04a60c318f37d2586b02587a26 SHA-1: 695dc190cd70d39a16a003400581353065f964af SHA-256: d8c12fb3fc8f75b90c2a11a84b190c7fb3736f08c78a45ab336bacd39f19d3b9

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications

The sample is an Excel file containing two Excel 4.0 macro sheets. The critical heuristic firing confirms the presence of these macros. While the macro content is heavily obfuscated and difficult to parse directly, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands upon opening the document. This is a common technique for initial payload delivery.

Heuristics 1

Excel 4.0 macro sheet (2 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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `61c86c6d83897319106ad1111b11750170a262e822e92dd4132e2d216c1b3436`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	1284 bytes
`xlm_sheet_01.bin` `c3b8db8f1200fbfa8d0fd068f7e0793a50b78e7cfbdd9a4987503d7a9bda3e74`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.bin	1169 bytes

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