Trickbot — Office (OOXML) malware analysis

Static analysis result for SHA-256 75963d78a7c18e2b…

MALICIOUS

Office (OOXML)

117.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: e9af0605d2e0b47b76d6b0f0a3e59f37 SHA-1: a6e9b0f8b25af84706084c091d40d234dbf20684 SHA-256: 75963d78a7c18e2ba94db8ec7137ea4388af2d4c24d47abf0df4db7a90b86ac7
250 Risk Score

Malware Insights

Trickbot · confidence 95%

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

The file contains multiple Excel 4.0 macro sheets with defined names and dangerous functions like FORMULA and HALT, indicating malicious intent. The macros construct a command to download a DLL using regsvr32 from the IP address 185.209.160.61 and execute it. ClamAV also detected this as a Trickbot downloader variant.

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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