Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 86bfa6a574902c68…

MALICIOUS

Office (OOXML) / .XLSM

45.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-04
MD5: c3ee540299a15b659dc4b169cfd19911 SHA-1: 7220caa4df7b90a51afa5ec774d9dd1207ecb8b1 SHA-256: 86bfa6a574902c68423527ab467b02e422d656d8fd560d0c3b64dfb3fa9bb433
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1218.010 System Binary Proxy Execution: Regsvr32 T1059.005 Command and Scripting Interpreter: Visual Basic T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, identified by the OOXML_XLM_MACROSHEET and OOXML_XLM_DANGEROUS_FN heuristics. The macros leverage the FORMULA API to construct and execute a command using regsvr32.exe to download and run a payload from one of the embedded URLs, such as http://narsanatanaokulu.com/wp-includes/WQHhwTuSM5flyMv9/. The ClamAV detection as 'Xls.Downloader.Emotet03220-9940726-0' strongly suggests the Emotet family.

Heuristics 7

  • Excel 4.0 macro sheet (3 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.Emotet03220-9940726-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9940726-0
  • 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 5 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://narsanatanaokulu.com/wp-includes/WQHhwTuSM5flyMv9/
    • https://ramijabali.com/licenses/44KGV1/
    • http://vipwatchpay.com/Isoetales/Mvlqx9YifBDaHH6e/
    • http://www.beholdpublications.com/home/GCKnZAKB3zz1qnN/
    • https://winnieswondersaviary.com/wp-content/BNzK17qzh1WQm/
    • https://rjssjharkhand.com/wp-content/ZddKK1KEaCO6BYbS/
    • http://narsanatana
    • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
94965f752a1e7be43d1bf315273deead3f139a3387887345fe87c8486a290891		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3704 bytes
xlm_sheet_01.xml
351feaae7418c65a74e6a0ba66009b604df9b81504ed5e5dbe43c90a37e65a77		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1278 bytes
xlm_sheet_02.xml
e7d03b45d335889b8dde35df06f3ab1a1e873e88cc653bc40b000e1458d4c807		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1152 bytes

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