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

Static analysis result for SHA-256 e72581f35043f4b6…

MALICIOUS

Office (OOXML) / .XLSM

120.1 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 75999b82582dff5a2257ee51b1978ae4 SHA-1: 776fc1aff9d4acec7bb815384505e4991d461802 SHA-256: e72581f35043f4b61450bd145fd9aad957fdb6110b2f85225751dc1081db840b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell

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

Heuristics 4

  • 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, 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.
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
07f4642ae693bcda0109647800937a545625151cf00c4004cbf3c380d0c360e6		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 744 bytes
xlm_sheet_01.xml
d0f00d5ec29552a4ac33f37541f0ec4947e2b9ca3e0e12d642423d0b6b2e1c40		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 207680 bytes

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