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

Static analysis result for SHA-256 ba6de3a75b3163fe…

MALICIOUS

Office (OOXML) / .XLSM

223.0 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 91615a636477965189d10d4cfa1d5916 SHA-1: 41c2f16c919d59ecc7d60b5d87ce599bc6aa1c99 SHA-256: ba6de3a75b3163fedc7fa5292f97558c53dbddb6b055363af7bb82a170367563
218 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

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, and EXEC to download and execute a script file located at C:\ProgramData\FAVlcKV.sct. The document also contains an external hyperlink to www.shipco.com, which may be used as a lure or for further stages. The use of Excel 4.0 macros and the execution of a 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
7cb454cd3a3ab61182a8e3af5a0460cd081cddaf605a914ed133a8afefe77de8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 901029 bytes

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