Dridex — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 24da86aa9324d111…

MALICIOUS

Office (OOXML) / .XLSM

216.5 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: bbbf5097ad620e1c5fc086dea200700c SHA-1: 64b30ec37556e53eb7bcd49684ad3946575ec28d SHA-256: 24da86aa9324d1111d69a2737083c9489f682c991fe9694a950a9dddf72cf796
250 Risk Score

Malware Insights

Dridex · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File Execution: Malicious File T1059.005 Command and Scripting Interpreter: Visual Basic T1218 System Binary Proxy Execution

This XLSM file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a strong indicator of malicious intent. The macros utilize dangerous functions like EXEC and HALT to download and execute a script file. The script path is constructed using character codes, resulting in 'C:\ProgramData\YeoeNxDw.sct'. The EXEC function is called with 'MSHT(C:\ProgramData\YeoeNxDw.sct)', indicating that the mshta.exe utility will be used to execute the SCT file, likely to download and run a second-stage payload. The ClamAV detection further confirms its malicious nature, identifying it as a Dridex downloader.

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
334ff2e40100c373e96bab7564f38685acc180eaa22d93f92c719b4174e4cc52		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 185758 bytes

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