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

Static analysis result for SHA-256 fec5dde9490b6ded…

MALICIOUS

Office (OOXML) / .XLSM

265.3 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 64a6adc922cc7c1d082cedc6470370dd SHA-1: 892b7b53c0156c3ac8b5b2eb1d07b1cdf3c70d65 SHA-256: fec5dde9490b6ded513d55c8a2c322f711433b87926fd03c60df61f7b6f89ac7
218 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1059.005 Visual Basic T1204.001 User Execution: Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an XLSM file containing Excel 4.0 macros. The macros utilize dangerous functions like EXEC and CALL to write and execute a script file located at C:\ProgramData\UYEhUORs.sct. The document also contains an external hyperlink to www.shipco.com, which may be part of a lure. The use of Excel 4.0 macros and the execution of a script from ProgramData are indicative of a downloader or initial access mechanism.

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
0197e406ce4191da3dbbdc2f30ef47b087e53db416807a540d68a8567ec22e02		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1600245 bytes

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