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

Static analysis result for SHA-256 a03f34e68bd72991…

MALICIOUS

Office (OOXML) / .XLSM

180.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 7cc15e9e54b0dbaf6c6075b373eda02b SHA-1: ce35f457dd32ec0c7fc6cf55f18d62d3d68b2aa4 SHA-256: a03f34e68bd72991b332c4f5950b7883f6858d35da8bd9207a423249b8519264
248 Risk Score

Malware Insights

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

The file is an XLSM document containing Excel 4.0 macros, specifically utilizing dangerous functions like REGISTER and CALL to download a payload from 'http://truemerit.io/databases/merit.php'. The presence of hidden sheets and the Auto_Open defined name further indicate malicious intent. ClamAV also identified this as a downloader variant.

Heuristics 6

  • Excel 4.0 macro sheet (2 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: REGISTER, GOTO, EXEC, RETURN 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.
  • ClamAV: Xls.Downloader.GreenEnable0921-9893703-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.GreenEnable0921-9893703-0
  • 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://truemerit.io/databases/merit.php
    • http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
e7fd2c7da91db17ab37ec5d5db0aefee1ba1a84e9da89c0b8bba88919a304caf		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 6025 bytes
xlm_sheet_01.xml
2b4c00a3a0366985e36c870635d0d18e75f1fd99d5eaca9abaf7ceeefd37bf79		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2761 bytes

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