Qbot Office (OOXML) / .XLSX malware analysis — malicious · 4fe687d82d8bf484

MALICIOUS

Office (OOXML) / .XLSX

117.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-24

MD5: a24ca6b493b90e5421639c99a43c54b8 SHA-1: e31b70c0c3105532655d219baf4dd711336a15d8 SHA-256: 4fe687d82d8bf484db77bf663b6a27983dceec94fe204b13e3cb5c5fa0566005

180 Risk Score

Malware Insights

Qbot · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file is identified as malicious by ClamAV with the signature Xls.Downloader.Qbot03220-9942292-0, indicating a Qbot downloader. The presence of multiple Excel 4.0 macro sheets (xlm_macrosheet) strongly suggests macro-based execution. These macros are designed to download and execute a second-stage payload, a common characteristic of Qbot droppers.

Heuristics 3

Excel 4.0 macro sheet (12 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.
ClamAV: Xls.Downloader.Qbot03220-9942292-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Qbot03220-9942292-0

Extracted artifacts 12

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `634354893576e307c65963ccace2b5e550032ed9362f8efca52602ab270a7938`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	1050 bytes
`xlm_sheet_01.bin` `5afafbf01f08461397defa63bddc057b80b257780a9236e908668beef68f4485`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.bin	482 bytes
`xlm_sheet_02.bin` `fd19c0386da3dd3c08345905679f48c054af85a8c94bed856e5388108422e105`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	2794 bytes
`xlm_sheet_03.bin` `0f6789a977a92c7b99385e78ab87d328344846dfcaa460b7d90345e138932489`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin	1196 bytes
`xlm_sheet_04.bin` `7d812db0fce9902a3d5229cfdfe5e8f22699c483faafb50592c6e9ddb517bbc3`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.bin	482 bytes
`xlm_sheet_05.bin` `b4ccc708800dd8bc23c880b7a894acc3eafef87cb2ef9efff43fd418c785af46`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.bin	482 bytes
`xlm_sheet_06.bin` `b662f6052e8802add465b0c459997e7886ea4cbcf0a375167ae9946a8090728d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.bin	482 bytes
`xlm_sheet_07.bin` `9d6b5d56174dc4eccbf897c65266832e8509b95cba25cc17d95701bffb300077`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.bin	562 bytes
`xlm_sheet_08.bin` `23c41dfad63fdcb812ba78a635dc1b8d3e5f556453cc45372f922931a01c41d4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet8.bin	442 bytes
`xlm_sheet_09.bin` `7547fa8e29fe1ff3ba5b446f2dabd0d80da1227f2aeb5a8c745081369650305a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet6.bin	442 bytes
`xlm_sheet_10.bin` `b12d5ed97fc7186c5b4baa331f7146f12375d285939841c26f4e9d0d4765a6ad`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.bin	783 bytes
`xlm_sheet_11.bin` `76289228588761679b2089219bfc2e48fe1593db5f0128b8b0dd690d39386a9a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet7.bin	393 bytes

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