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

Static analysis result for SHA-256 8d4547fa89823eb3…

MALICIOUS

Office (OOXML) / .XLSM

208.4 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: ab667c342e83997121b7a9c78f340e23 SHA-1: 1fca4d57206e1a7f9dfff6b9bd69d64d593ce176 SHA-256: 8d4547fa89823eb34301fcf14ba38a04af3285937c86b8f615fe421dee808f87
218 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: User Execution: Malicious Macro T1059.005 Command and Scripting Interpreter: Visual Basic T1059.001 Command and Scripting Interpreter: PowerShell T1218.011 System Binary Proxy Execution: Rundll32

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FOPEN, FWRITE, FCLOSE, and EXEC to write and execute a script file located at 'C:\ProgramData\ITWUoFTF.sct'. The document also contains an external hyperlink to 'http://www.shipco.com/ecommerce/sch/scheduleindex.php', which may be related to the lure or a download source. The use of Excel 4.0 macros and the execution of a local script file indicate a downloader or dropper functionality.

Heuristics 7

  • 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.
  • 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
  • External hyperlinks (1) low OOXML_EXTERNAL_HYPERLINKS
    Document contains 1 external hyperlink — clickable URLs are stored as external relationships. First target: http://www.shipco.com/ecommerce/sch/scheduleindex.php
  • 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://www.shipco.com/ecommerce/sch/scheduleindex.php
    • 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
0735a6c3d9cf45dd149d07714a1909869e13c163479c0b9c7a0d0f94585581db		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 791023 bytes

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