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

Static analysis result for SHA-256 6b0e27d742c289a0…

MALICIOUS

Office (OOXML) / .XLSX

101.7 KB Created: 2020-06-23 11:38:23 UTC Authoring application: Microsoft Excel 16.0300
MD5: 8cc8ead6ff34f83c8e3fa39e82417500 SHA-1: 23ccc564fa504319638b07a951996e029be8ef0b SHA-256: 6b0e27d742c289a0a036ba8ecda0b7ec25ef6661d01d216847a8ec88263e666c
210 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1203 Exploitation for Client Execution

This XLSX file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FORMULA.FILL, REGISTER, and HALT, which can be used to download and execute arbitrary code. The document also contains a lure to enable content, indicating an attempt to bypass security measures and deliver a payload.

Heuristics 6

  • Excel 4.0 macro sheet (1 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.FILL, REGISTER, HALT 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 12 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 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
6f4aed1ae96430b09ce4437ce30fffe68b891f4c121f1aa8abf5bd208f469115		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 166393 bytes

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