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

Static analysis result for SHA-256 7b559a391e839332…

MALICIOUS

Office (OOXML) / .XLSM

321.7 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 5a0232a75114faf64a5098459954ff49 SHA-1: e81c61b3f70bac962c398ec8e1a03ca3be472316 SHA-256: 7b559a391e8393323f1660f3bf80fb5a46045593cedc9b8459dbc9262ace77cb
190 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: User Execution: Malicious File T1059.005 Command and Scripting Interpreter: Visual Basic T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, which are known for their ability to bypass security controls. The macros utilize dangerous functions like FOPEN, FWRITE, and EXEC to download and execute a script file. Specifically, the macro reconstructs the path 'C:\ProgramData\LqJPQXcz.sct' and uses FOPEN to prepare for writing to it, indicating a payload download and execution attempt. The use of these low-level functions suggests a downloader or initial access stage.

Heuristics 5

  • 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: FOPEN, FWRITE, FCLOSE, EXEC, 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.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
d79ac019f241a8701ec4d293297201b22da5a56bc50fe041be969b4d540a1f4e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1645306 bytes

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