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

Static analysis result for SHA-256 d9be3d80a6baf028…

MALICIOUS

Office (OOXML) / .XLSM

34.7 KB Created: 2020-06-01 00:02:41 UTC Authoring application: Microsoft Excel 16.0300
MD5: bcaf919dc38a2072c552e2ff938e8e07 SHA-1: 683da305b34eca7c7d5cef962b9dd920e26f7fe9 SHA-256: d9be3d80a6baf028c62f24d8b5308db44bb8d3723b63ff4aba8be4d34f5b7924
210 Risk Score

Malware Insights

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

This XLSM file contains Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macros utilize dangerous functions like RUN, FORMULA, CALL, and HALT, which are capable of executing arbitrary commands. Specifically, the macros contain multiple RUN commands, such as RUN($J$143), which are likely used to download and execute a second-stage payload. The presence of a SE_ENABLE_LURE heuristic suggests the document attempts to trick the user into enabling macros.

Heuristics 6

  • 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: RUN, FORMULA, CALL, 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 7 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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
b41472b6dc0ee3e7d2a5cf8a2238fbf0301d6bfc254ccf205328f5dbc0ce9098		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 78124 bytes

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