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

Static analysis result for SHA-256 f4b3cf38f5242471…

MALICIOUS

Office (OOXML) / .XLSM

197.7 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 119e925268c788435867db6e9adb2928 SHA-1: 5cd558a773e2bdcea93cd0b66f28af2a7f72b5a1 SHA-256: f4b3cf38f5242471c9c078b306c6d62e939a58c5ce826d55a23c9b80a7ee4384
310 Risk Score

Malware Insights

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

This XLSM file contains multiple Excel 4.0 macro sheets, including an Auto_Open macro, which is a common technique for initial execution. The macros utilize dangerous XLM formula APIs and contain strings like URLDownloadToFileA, indicating the script's intent to download and execute a second-stage payload. The presence of hidden worksheets further supports the malicious nature of the file.

Heuristics 7

  • Excel 4.0 macro sheet (6 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: FORMULA, GOTO, 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.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • ClamAV: Xls.Downloader.GreenEnable052-9863734-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.GreenEnable052-9863734-1
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 6 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 — context-specific rules above attribute URLs they actually evaluated; this rule lists URLs that were present in the bytes but were not otherwise tied to a specific finding.
    URL http://schemas.openxmlformats.org/spreadsheetml/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://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
e26278d9df62929caddc39c2675d1a93c805965a35896b4c4240468b728373e2		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1190 bytes
xlm_sheet_01.xml
b7f12cc848c0344b1a5988c23e28d66931cabf93578aa111050b66b24515bc26		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 3173 bytes
xlm_sheet_02.xml
885dac7b9ca2b9e8230baf49dad2ec27d3477b45eb4960d36b69b3166c4addb8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2299 bytes
xlm_sheet_03.xml
14198d56b3e501819788d2ba3deb676eae1c92f5b98789f221df62060b8b227d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1481 bytes
xlm_sheet_04.xml
37cb7aa1e44520111e622e68f961c06b193624824122bd99088e7c0d058baf3c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1469 bytes
xlm_sheet_05.xml
68e2eada477a01dd45889d7781ac27297df589224a5824d7ff63a37df7f5bc75		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1476 bytes

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