Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 ae3ac0659210f9f6…

MALICIOUS

Office (OOXML) / .XLSX

83.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: fb08cdbf451e3515e7acb5a56b48d782 SHA-1: 2343c036bc34f0a5f029f524b4a647a5ca01d30f SHA-256: ae3ac0659210f9f66b73bb14858d53a215ed91ef3c5b812c671fd4e824ee150a
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1218.011 System Binary Proxy Execution: Rundll32 T1105 Ingress Tool Transfer

The sample is an Excel 4.0 macro sheet, identified by ClamAV as 'Xls.Downloader.EmotetExcel01223-9936530-0'. It utilizes dangerous XLM formula APIs, specifically 'FORMULA', to call 'rundll32.exe' with arguments that include URLs pointing to potential payloads. The reconstructed URL for downloading is 'http://15.237.135.38/dza9hr/kjt6/'. The macro also references '..\\\dwa.ocx' and 'rundll32.exe SysWow64\\LDownloadToFileA', indicating a download and execution chain.

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://15.237.135.38/dza9hr/kjt6/
    • http://wateringcanreview.xyz/wp-includes/css/qky11a/
    • http://cakemixturereview.xyz/wp-includes/U2ayYVCPRhWqERyw4/
    • 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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