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

Static analysis result for SHA-256 9a59e089d7b593c0…

MALICIOUS

Office (OOXML) / .XLSM

94.6 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: cf8cbce9bb25d9081b2da19c6f1c1c70 SHA-1: e014ec63d11a673fd6a655cb20055a723eba2fe5 SHA-256: 9a59e089d7b593c0b0651ad43945f19c10c67719b7e01814f4007f253db6e286
200 Risk Score

Malware Insights

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

The file is an XLSM document containing 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 functions like CALL and EXEC, which are commonly used to download and execute payloads. The extracted URLs suggest a pattern of malicious domains likely hosting the second-stage payload. The macros are designed to execute automatically upon opening the document.

Heuristics 5

  • 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: CALL, EXEC, 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.
  • Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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
4fd8ecee860e57399ce62e9508bad9e80e01a450507f07d5419da1b61aa2d8d7		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 212614 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 shell/COM execution token(s).

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