Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 c25a24f0f944de44…

MALICIOUS

Office (OOXML) / .XLSX

143.7 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 097bc1db62e3e6dc1d74f98b6d91bb70 SHA-1: 0e3e0c6d974a964ebe171aa518c1d54a5dde4c40 SHA-256: c25a24f0f944de44c05db6bf7cdafb97f6b3a9d4485f4984aec2baa919c2ab0b
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 PowerShell T1204.002 Malicious File T1059.001 PowerShell T1218.011 Rundll32

This XLSX file contains Excel 4.0 macros, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_DANGEROUS_FN' heuristics. The macros utilize dangerous XLM functions like FORMULA to call external APIs, which are used to download and execute payloads from URLs such as 'http://tan4j.com/wp-content/eeKyqAfNAS0VWzH/'. The 'SE_LOLBIN_RUN_COMMAND' heuristic further confirms the use of 'rundll32.exe' with a concatenated URL, suggesting a download and execution chain. The ClamAV detection 'Xls.Downloader.EmotetRed022215-9938912-0' strongly suggests the Emotet family.

Heuristics 7

  • Excel 4.0 macro sheet (7 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.EmotetRed022215-9938912-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetRed022215-9938912-0
  • 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 9 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 https://esthetravel.com/762tv0z2/cache/S1r2qBwOXEnwkc7/
    • 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 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
845190ff95687dd3bed60f8155a4703d187c9ac3d57c95b5f1e5fbccfcda8bf1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3818 bytes
xlm_sheet_01.xml
17a44bab46f03e771bd6542298156e3f6d09e434efc242a62b869dfb808c8fe0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1339 bytes
xlm_sheet_02.xml
e0e53f2efa6401d85f42fc271b8a5f25f093236955ae9e2f8aff086ade287b72		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1334 bytes
xlm_sheet_03.xml
99c0021f265b2512c81119e70583856c3b88d92cfcf4088dd76957bd454698ca		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1337 bytes
xlm_sheet_04.xml
505da860283599ae30bb243e4b86ce81f7bcbf678c783ee47ffef058c21fdfa5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet4.xml 1341 bytes
xlm_sheet_05.xml
33833c2bb127cd3da704c0fa39beca9ede4ef247ba80706d40a7c8cb5fdddbee		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet5.xml 1256 bytes
xlm_sheet_06.xml
9db93655cb6fd9e30bf1d3ffbd4e22d858cd95d48236de02bbc820699d35abf8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet6.xml 1177 bytes

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