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

Static analysis result for SHA-256 73b3bd3f479443db…

MALICIOUS

Office (OOXML) / .XLSM

81.2 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: e101aad6f65de564f1a0138bbd0cc841 SHA-1: c34414ffb68df0d4ac4a8baf4e39fd132952cce0 SHA-256: 73b3bd3f479443db5798d6a96125d0c0ae5d835e2d5b2bc20741f11894fe6276
182 Risk Score

Malware Insights

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

The file is an XLSM document containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FORMULA and CALL to download a second-stage payload from the URL 'http://rcwj22jxyvt03swnlt.xyz/grays.gif'. The presence of the Auto_Open defined name indicates that these macros will execute automatically upon opening the document.

Heuristics 4

  • Excel 4.0 macro sheet (3 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, CALL, HALT, EXEC 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.
  • 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://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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
7cc29e0426c044da329e809d130552193749e3486fd84097688f127f76120087		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5778 bytes
xlm_sheet_01.xml
5e0b317bc9eef478a9b391aa848d4ca25c6a2921bbc6af4ad6fc140f76188572		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 963 bytes
xlm_sheet_02.xml
e3b9f480f3ca4a979aa292a90d1c11a4dcba6e74c7c714e8152c423050cc3e40		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3017 bytes

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