Dridex — Office (OOXML) malware analysis

Static analysis result for SHA-256 121a4ee4456e0b6e…

MALICIOUS

Office (OOXML)

213.7 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: d984c49c012711a63140663b2a65fa9e SHA-1: 8358af301387155105aed430a9e6ba299978a496 SHA-256: 121a4ee4456e0b6ed04210e59b5dbb7234371102f7822a433ac41f30e0528537
250 Risk Score

Malware Insights

Dridex · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically using the Auto_Open defined name, which is a critical indicator of malicious intent. The macros leverage dangerous functions like EXEC and HALT to execute a script located at 'C:\ProgramData\KAZrsgYWLlqGaEI.sct'. ClamAV also detected this as 'Xls.Downloader.DridexCyan08210-9887648-0', strongly suggesting a Dridex downloader variant.

Heuristics 6

  • Excel 4.0 macro sheet (1 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: EXEC, HALT, FOPEN, FWRITE, FCLOSE 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.DridexCyan08210-9887648-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.DridexCyan08210-9887648-0
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
d105ab6b2b8f26ac3c17dbc28c8c9ec1b2d016e766a16edbbb4930133c6019fa		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 150087 bytes

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