Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 2f4079c074d822a3…

MALICIOUS

Office (OOXML) / .XLSM

26.7 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-06-23
MD5: 06c418be1e5a895173226a8e7a05dbd2 SHA-1: 4543fb5b819dcbfe21934585311071c194abc790 SHA-256: 2f4079c074d822a33c911efbb918c16ccc0a2bc7e803d69fe36e8e08205913cf
270 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is an XLSM file containing Excel 4.0 macros, specifically triggering an Auto_Open defined name. Critical heuristics indicate the use of dangerous XLM formula APIs like CALL and EXEC, which are used to download and execute payloads. The macros reconstruct the URL 'http://cashmailsystem.com/upload/xsVEPr4708Uk/' to fetch a second-stage payload. The ClamAV detection as 'Xls.Downloader.Emotet' strongly suggests the Emotet family.

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, CALL, EXEC, RETURN 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.Emotet-aa87d5786a858772-9953435-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-aa87d5786a858772-9953435-0
  • Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 6 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://bosny.com/aspnet_client/jBnf4JopKAybRZb7U/
    • https://aysbody.com/catalog/bwC1Xuouo/
    • http://cashmailsystem.com
    • http://www.thuybaohuy.com/wp-content/6O4JMYNFBxOXta/
    • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
706b03c95da6c5086ef554e8b811298a83001dd428c9126400fdf3eb3e836430		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4752 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 shell/COM execution token(s).

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