Office (OOXML) / .XLSX malware analysis — malicious · 8e1926ea256c3e43

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 059c83c68a2c278d4508c10c093eaa5e SHA-1: 168d862d6a5b3cba01396a309eaf593e0b88312b SHA-256: 8e1926ea256c3e439c4dc17f82443c716893dd43b287f771c2872565a7f5901a

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an OOXML XLSX document containing multiple embedded Excel 4.0 macro sheets. These macro sheets are indicative of an attempt to execute arbitrary commands or download further payloads. The heuristics indicate the presence of XLM macros, which are often used for initial execution. Due to the truncated nature of the script excerpts, the exact functionality and IOCs cannot be definitively determined, leading to a lower confidence score.

Heuristics 2

Excel 4.0 macro sheet (3 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.
XLSB international XLM macro sheet hidden in .xlsx critical OOXML_XLSB_INTL_MACROSHEET_IN_XLSX

OOXML package is named .xlsx but contains XLSB workbook parts and an international Excel 4.0 macro sheet. This hides XLM macro execution from scanners that trust the extension or only inspect XML worksheet parts. The technique is macro execution, not a document-parser CVE.

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `a5a5a283f44af341ea536e79ac8abfdec4535cd26259fee4aaeddf6922c005d4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	5899 bytes
`xlm_sheet_01.bin` `b503ede42cdf904e2af5c974f8dc360e708418fa45acca6ff4722bf393f0454f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin	1158 bytes
`xlm_sheet_02.bin` `d31123f9a07e81ccf791dca8e5e37ecc4c2d30b43e94ccbd560bc857c4b313d4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.bin	6203 bytes

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