Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 e19c4cdeb5c2e941…

MALICIOUS

Office (OOXML) / .XLSX

83.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: d1eedd8bfac41c6f280053c59bb48310 SHA-1: 7abf86c72bfc605165a5e997172ac5ca4ee53f92 SHA-256: e19c4cdeb5c2e9417e8976342dcf2494d337be7e4f6be1f465e9eacf998a6d5d
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

This Excel 4.0 macro sheet utilizes dangerous functions like FORMULA to download and execute payloads. The macro attempts to download content from multiple URLs including 'http://laserjetprintersreview.xyz/wp-includes/BJ6yUJ/', 'http://yuanbinglun.com/www.yuanbinglun.com/7kKwqmxRWQK0OLi/', and 'http://2021.posadamision.com/wp-admin/IoqaL08/'. It also constructs commands involving 'rundll32.exe' and '..\dwa.ocx', indicating a downloader functionality. The ClamAV detection as 'Xls.Downloader.EmotetExcel01223-9936530-0' strongly suggests the Emotet family.

Heuristics 7

  • 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: FORMULA 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.EmotetExcel01223-9936530-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetExcel01223-9936530-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 3 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://2021.posadamision.com/wp-admin/IoqaL08/
    • http://yuanbinglun.com/www.yuanbinglun.com/7kKwqmxRWQK0OLi/
    • http://laserjetprintersreview.xyz/wp-includes/BJ6yUJ/
    • 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
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
94ce481067ff50aad11a63e7c0d34887a339fe2ee9932e266cd1503beaa545b9		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3034 bytes

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