dridex — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 44696d1a44cffa1e…

MALICIOUS

Office (OOXML) / .XLSM

138.0 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: a4d17397ad271e2442dc55c78175b70c SHA-1: 320a599c802bbbd134b0dc53af9e255fb12258db SHA-256: 44696d1a44cffa1e94ba3e95bfad2ba52dd33e0386bd3773860caf0e70cc6692
250 Risk Score

Malware Insights

dridex · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, specifically triggering critical heuristics for macro sheets, Auto_Open, and dangerous functions like FOPEN, FWRITE, and EXEC. The ClamAV detection explicitly names it as 'Xls.Downloader.Dridex122100-9913248-0', strongly indicating the Dridex family. The dangerous functions are used to download and execute a second-stage payload, a common characteristic of Dridex droppers.

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: FOPEN, FWRITE, EXEC, RETURN 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.Dridex122100-9913248-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Dridex122100-9913248-0
  • 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
0be9f644d377adf819c5f300a7eae2365e3fb517cdc682dfe80dc2886c7869c1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5496 bytes

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