Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 34dc98623cca746f…

MALICIOUS

Office (OOXML) / .XLSX

144.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 823df93562a6917f67d185c3a4fec169 SHA-1: 19870eb920a41b242bcec3c92f44c6f9b71ff8f6 SHA-256: 34dc98623cca746fbe477b37533cfea46fc2842cee2a779c8cd9c7747bfc4502
270 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 PowerShell T1218.011 Signed Binary Proxy Execution: Rundll32 T1059.001 PowerShell T1105 Ingress Tool Transfer

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by multiple critical heuristic firings including OOXML_XLM_MACROSHEET and OOXML_XLM_DANGEROUS_FN. The macros are designed to download and register a DLL payload using rundll32.exe. Specifically, the macros construct URLs such as "https://7jcat.com/wp-content/cQO3vdPQavJrf2UrCW/" and "http://desayunosdesde.casa/wp-content/lyNShWgYN7F/" to fetch a file named "..\dwd1.ocx", which is then registered using "rundll32.exe \Windows\SysWow64\ regsvr32.exe ..\dwd1.ocx". The ClamAV detection also confirms this as Emotet. The use of Excel 4.0 macros and the download/registration pattern are characteristic of Emotet.

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
  • External relationship medium OOXML_EXTERNAL_REL
    External target in xl/externalLinks/_rels/externalLink1.xml.rels: /Users/Admin/Desktop/File/4f/Сir-ZV/Cir/1.xlsm
  • 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 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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