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

Static analysis result for SHA-256 eec108843fcb466d…

MALICIOUS

Office (OOXML) / .XLSX

158.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: ea52c53b71861b6a66233536a97f51a1 SHA-1: ccb86e2bf9b9557a76e960dbd60092ab31d0ae90 SHA-256: eec108843fcb466d424001532bc3344093b399ec813cfd9134dae584e5080543
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic, Visual Basic for Applications, and VBScript T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_AUTOOPEN_DEFINEDNAME' heuristics. The 'OOXML_XLM_DANGEROUS_FN' heuristic confirms the use of dangerous XLM formula APIs like FORMULA.FILL, which are used to construct and execute commands. The FORMULA.FILL function appears to be assembling a string that likely resolves to a URL, which is then used to download a second-stage payload. The presence of two unknown URLs further supports this. The macros are likely intended to download and execute a malicious payload from one of the provided URLs.

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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