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

Static analysis result for SHA-256 565dfd3200e21dfd…

MALICIOUS

Office (OOXML) / .XLSM

84.2 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: d11d06a51780779d54e8377fa629e7b5 SHA-1: f999f091985727ab69660283a8e7422ce407756c SHA-256: 565dfd3200e21dfd7b4386da57389de7ef487a886c4f605fd4d5ae58c761c5eb
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell

The sample is an Excel macro-enabled spreadsheet (XLSM) containing Excel 4.0 macros. The heuristics indicate the use of dangerous functions like CALL and EXEC, which are commonly used to download and execute arbitrary code. The document body contains URLs that are likely used to fetch the malicious payload. The presence of Auto_Open and the use of CALL/EXEC point to an automated execution flow designed to download and run a second-stage payload.

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
6bb1fa7b25c4a31dd2d66243f24bc2b4809a5ecf6b1ca9480c724b6e46bd7687		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 238359 bytes

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