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

Static analysis result for SHA-256 feeb201d7b282cd4…

MALICIOUS

Office (OOXML) / .XLSX

158.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: 39e32b9a4ea2c05c6f5aa2f5e3084195 SHA-1: 7237606738f595e6a9184880308a181a2821d205 SHA-256: feeb201d7b282cd4a90dab6c285fa658f0780e5906d5f2e76f96d90768f00aac
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains multiple Excel 4.0 macro sheets, including one with an Auto_Open defined name, indicating it is designed to execute automatically. The macros utilize dangerous XLM formula APIs such as FORMULA.FILL to construct and execute commands. Specifically, the FORMULA.FILL function is used to concatenate strings from various cells, likely forming a URL to download a second-stage payload. The reconstructed URL appears to be "https://biopaten.no/xeBP8Oj5/gg.html" or "https://beartoothkawasaki.com/QJT19jhtwHt/gg.html", which are suspicious. This indicates an Ingress Tool Transfer (T1105) attack pattern.

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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