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

Static analysis result for SHA-256 f06910daadc7c66c…

MALICIOUS

Office (OOXML) / .XLSM

96.0 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: 4dd14d22cd0272ae24128bb1356a842c SHA-1: abf7d941f4ebf949816c5576060bfce76f836ae9 SHA-256: f06910daadc7c66c8e9064d0719ed6727d69c1f04ab13566cadbb6e7a9f52a7e
200 Risk Score

Malware Insights

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

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like CALL and EXEC to directly interact with the Win32 API, enabling the download and execution of arbitrary code. The embedded URLs are highly suspicious and likely serve as the source for the second-stage payload. The use of these functions and the presence of suspicious URLs strongly indicate a downloader or droppper functionality.

Heuristics 5

  • Excel 4.0 macro sheet (2 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: EXEC, HALT, WORKBOOK.HIDE, FORMULA.FILL, CALL 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
086120f5b0b7d67fd4b0845ea344f16dfb1909743259959239330ffc5d49f973		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 209574 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 shell/COM execution token(s).
xlm_sheet_01.xml
b37559ae8e8ebd485f6882c0587e1d8a78ced73936d04fb82f4bd4453af8aecb		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 5820 bytes

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