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

Static analysis result for SHA-256 e0f0a1b5feb22d8e…

MALICIOUS

Office (OOXML) / .XLSM

261.9 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: c4eb5f0e2122795a05d0bb4bb84e42bf SHA-1: 9e5b043a056a7b20e03b463a341d2c1148b83e51 SHA-256: e0f0a1b5feb22d8e2010d7adb0639b5e959a75005cf90dae3631e1484d2a09ec
190 Risk Score

Malware Insights

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

This XLSM file contains Excel 4.0 macros that leverage dangerous formula APIs like FOPEN, FWRITE, and FCLOSE to write a script to disk at C:\ProgramData\EjsJftUjdlOx.sct. The EXEC function is then used to execute this script. This indicates a downloader or dropper functionality, aiming to execute a second-stage payload.

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
9d873ec96a72e72a6357730f6223caa740426dc1c8236e67978356e5ff4469d3		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 814667 bytes

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