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

Static analysis result for SHA-256 9872498872843b5a…

MALICIOUS

Office (OOXML) / .XLSX

82.1 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: bcb5f8c6da6103a5bbd4891095f807af SHA-1: fccc0e19a042d3da003bc4184b32c784ca5dfd14 SHA-256: 9872498872843b5aae813d390df3e46ae02a4cc994ade723e4f5ba2973043fb7
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like CALL and EXEC, indicating an intent to download and execute a second-stage payload. The embedded URL, though malformed, likely points to the location of this payload. The document body contains a string that appears to be part of a URL, further supporting this.

Heuristics 4

  • Excel 4.0 macro sheet (3 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, CALL, HALT, EXEC 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.
  • 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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
750216d98b571028196caa5db2d00d1d865d416953bfdc8d348887b876ac8299		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 19711 bytes
xlm_sheet_01.xml
d30d0bdbdc3063e69afc7d3c6401429aac87693165a049927be503c06d2c964c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1419 bytes
xlm_sheet_02.xml
644ddaecdc2c5458cffc5ad58ed19949086a06cf10b478a5857d1c4cd8813551		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 6156 bytes

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