Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 cfa0fe012f82f993…

MALICIOUS

Office (OOXML) / .XLSX

158.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: 3577e6a16514d58409f6756fff740332 SHA-1: 7369118f653a2ee4aacf6d8bc88b42d82946279f SHA-256: cfa0fe012f82f993ed70fa3ddc9ff1e31501686b723107d4e3cd1de5794722ee
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1105 Ingress Tool Transfer

This XLSX file contains multiple Excel 4.0 macro sheets, including one with an Auto_Open defined name, indicating it is designed to execute automatically upon opening. The macros utilize dangerous functions like FORMULA.FILL to construct and execute commands, likely to download and run a second-stage payload from the embedded URLs. The use of these functions and the presence of Auto_Open strongly suggest a malicious intent to compromise the user's system.

Heuristics 5

  • Excel 4.0 macro sheet (5 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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FORMULA, HALT, FORMULA.FILL critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://biopaten.no/xeBP8Oj5/gg.html
    • https://beartoothkawasaki.com/QJT19jhtwHt/gg.html
    • http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
15fbfe55b20413f92e6ae6dcaa5199ef4834995471413702ff1b1894f486343d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 11346 bytes
xlm_sheet_01.xml
01be081374433318ab060c7d9534b134366d414e43d756214d58deb1a7557a22		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1807 bytes
xlm_sheet_02.xml
4942d78e9a4c26c9352582ba044fbdd7b5e434ac67308d3cb59b8725b48e9b99		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 1777 bytes
xlm_sheet_03.xml
a6863ce46a6a991745232b05bc1b5af380056ae05155ba24221669ae920dc1d9		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1460 bytes
xlm_sheet_04.xml
7a65a9a19541a783d2364e0cc237ab353fd49b12ac69aaaae5e6996c7d787d37		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1558 bytes

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