Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 f628025f02f96caf…

MALICIOUS

Office (OOXML) / .XLSM

21.2 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-22
MD5: 1bd25109bf90e5ec8accdae19e3cc7b8 SHA-1: a3a8ff3d91fd0643c7e47c27ba5094fef9473b80 SHA-256: f628025f02f96caf3c2518dcae0b4eac91f8275a1cbd67cc0fa89d6f8a888c87
250 Risk Score

Malware Insights

Emotet · confidence 95%

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

This XLSM file contains Excel 4.0 macros, specifically utilizing the FORMULA API, which is a known technique for downloading and executing payloads. The macros construct strings to form URLs and executable filenames, such as "http://beetle-j.jp/wp-admin/ErM4mW05tdj/" and "regsvr32.exe" which is then used to execute "rfs.dll". This behavior is consistent with Emotet's typical download and execution chain.

Heuristics 6

  • 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.Emotet03220-9941789-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941789-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 4 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://beetle-j.jp/wp-admin/ErM4mW05tdj/
    • http://e3technology.in/2checkout_integration_php/rDcr1Wl90WWA9M/
    • http://bjornbol.dk/wp-includes/ve4cnkjsUMWXC5Cb2bJ/
    • http://bebesel.com.tr/cgi-bin/1wy3oHO/
    • https://brutobrasil.com.br/pdf/toO18cIP3/
    • http://biesenbeek.nl/familie/b6KKlrfH75GD3dHojB/
    • http://bcelectronics.co.za/wp-content/grKnz1V/
    • 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
f9ef0dd03a642623a126a648a3e3b498d8403d13558799b8b55ca81a239f78e5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3968 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.