Trickbot — Office (OOXML) malware analysis

Static analysis result for SHA-256 d218c6d6b4e3d537…

MALICIOUS

Office (OOXML)

117.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: 7c631034cc969001a4b879af237d696e SHA-1: ef2eee916d01dd2a961f692573c13364b3dae45e SHA-256: d218c6d6b4e3d537c541aa4d9e9db1bfaaedc1ac0c490343cf5a3ef70c594c34
250 Risk Score

Malware Insights

Trickbot · confidence 95%

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

The sample contains Excel 4.0 macros, specifically using the dangerous FORMULA and EXEC functions to download and execute a second-stage payload. The macro attempts to download a file from 'http://185.209.160.61/2.php' and save it as '..\reyytutrutr.dll', then execute it using regsvr32. This behavior is consistent with Trickbot downloader modules.

Heuristics 6

  • Excel 4.0 macro sheet (5 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, 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.
  • ClamAV: Xls.Downloader.Trickbot07210-9880007-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trickbot07210-9880007-0
  • 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://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 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
d97a2a9150e74229083efcca5f2f8b640baf7423626a395c64177c1459168ed4		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1242 bytes
xlm_sheet_01.xml
137e6de0500e6ed38a970730e13f0f763837d1b754cf2efb03a4547960b665a4		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 1224 bytes
xlm_sheet_02.xml
caa60bc2fa567384b9f9695ddaf8a0289adcf6e6d71e5d9e3081ecac07c68c58		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1254 bytes
xlm_sheet_03.xml
1873629191b88439c05dd10fb14a7ad37d1d4d6f30599b8a33e637bdca08d84d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 228692 bytes
xlm_sheet_04.xml
cd97a877378a69fe2c8f0bcdbb32f607765e8a3e95278b42bad9922c9430ebb8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1477 bytes

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