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

Static analysis result for SHA-256 a3abaec7e03404be…

MALICIOUS

Office (OOXML) / .XLSM

106.9 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 4cc71a9e0ffaa6e070ddd5be07828a23 SHA-1: 2e5b8984a559c9327f47665c1322859026d60912 SHA-256: a3abaec7e03404bee5dab6c07a8f79dd72b21b7bb3c376b4af9b1fc101962d6b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic, VBScript, and JScript T1204.002 Malicious File

The sample is an Excel macro-enabled spreadsheet (XLSM) containing Excel 4.0 macros. The heuristics indicate the use of dangerous XLM functions like CALL and EXEC, which are commonly used to download and execute arbitrary code. The document body contains URLs that are likely part of the payload delivery chain. The presence of Auto_Open suggests automatic execution upon opening.

Heuristics 4

  • 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, FORMULA.FILL, 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.
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
9cf577639483a84c18a4933d3e27f255a331eea77d6198cb6ba582a5fa65de0a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 240381 bytes

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