Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 da40466ddca2530a…

MALICIOUS

Office (OOXML) / .XLSM

49.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-15
MD5: 12458120dbc39a746de50f0d2d3cbf85 SHA-1: 06a27595a907ef244c01d88264501204d67abd1c SHA-256: da40466ddca2530afee8de6b05d1370c6156c154bd381ca488aa0b58f179730e
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 Link: Malicious File T1105 Ingress Tool Transfer

The sample is an XLSM file containing Excel 4.0 macros, as indicated by multiple critical heuristic firings including OOXML_XLM_MACROSHEET and OOXML_XLM_DANGEROUS_FN. The macros utilize the FORMULA API to construct and execute commands. The DOC BODY excerpt reveals that the macros are designed to download a payload from one of the provided URLs, specifically reconstructing the executable name 'regsver32.exe'. This behavior is consistent with Emotet's typical download and execution chain. The ClamAV detection also explicitly names Emotet.

Heuristics 6

  • 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.Emotet03221-9941792-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03221-9941792-0
  • 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://arealama.com/assets_template/58DBYXQh01ATcsKY/
    • http://antaoco.com/wp-admin/QpyjXPLrEXf3R9/
    • http://www.automatic-taps.com/Templates/TyJj6dRjzqE/
    • http://arkamani.net/administrator/KIZXGmaRTF6N3qQqH/
    • https://www.artificium.es/blogs/mu8yHJ/
    • https://www.manchesterot.co.uk/about-us/fxVCCMDni/
    • http://www.atara.com.tr/Template/595vJ91nQx/
    • 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
561bd2ad03d5ff349d3a0a4fbda71b956dd8d97a0dbce4e25549bf8a7721c5df		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4049 bytes
xlm_sheet_01.xml
4f892349a6f0ce9450df5d764f02eea0a737d43225bc39e0b3e39eaafe266901		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1276 bytes
xlm_sheet_02.xml
f8dcec9dac216a8c4fc7140768d73598afe199c381abfb2f58ad13ed8f5733f6		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1152 bytes

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