Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 95590bd82760d31a…

MALICIOUS

Office (OOXML)

83.4 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 37c01fd4852355142de8f198f9edb17b SHA-1: 557e58c3f13a1e61a6d75554519e902df2486c30 SHA-256: 95590bd82760d31ad26ad35b1286de7d67bc3ef195488b10aeb9870ee9d28419
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, indicated by critical heuristic firings for XLM macrosheets and the use of dangerous functions like CALL and EXEC. The macros construct a URL and filename, then use the CALL function to download a DLL from 'http://162.248.225.97/1.php' and save it as '..\iuretiu.dll'. This indicates a downloader functionality, likely to fetch and execute a secondary payload.

Heuristics 5

  • Excel 4.0 macro sheet (4 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: HALT, FORMULA 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.
  • 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://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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
d505811de5a883bedf8e0c2084c2b3d64cec37da9aca77dc270e4e2ea6d7486d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1456 bytes
xlm_sheet_01.xml
a8b153a062d4aa47a7768cbe416affb98aae83e032b07f2f3a7351700d9ff620		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1494 bytes
xlm_sheet_02.xml
cdf41698cded2e38132966777a3663575d2cfd1ea535f5505f7b546338e5a1c1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1386 bytes
xlm_sheet_03.xml
5e66e28f48eff5fa338d6f58cf0e9b1464f6c796c9bdf00ca35e20bac7f14dbc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 1510 bytes

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