Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 944981d4724b60c8…

MALICIOUS

Office (OOXML) / .XLSM

69.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-02-26
MD5: 7199aa85a153ec64d4f988cafe295434 SHA-1: 496486df72f6b4afa178ed2e482d2b0feaedd529 SHA-256: 944981d4724b60c8dcf446fbcf3ac465f5edb9c35d5400d36fa3a99750be7e15
270 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 PowerShell T1059.001 PowerShell T1204.002 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 dangerous functions like FORMULA to construct and execute commands. The reconstructed command string indicates the intent to download a payload from one of the provided URLs using regsvr32.exe and save it as 'aua.ocx' in the Windows directory. This behavior is characteristic of the Emotet banking trojan family, which often uses macro-enabled documents for initial infection.

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.Emotet03221-9940728-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03221-9940728-0
  • External relationship medium OOXML_EXTERNAL_REL
    External target in xl/externalLinks/_rels/externalLink1.xml.rels: /Users/Admin/Desktop/File/13j/ZV/ZV.xlsm
  • 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 https://vasilestudio.com/wp-admin/pZ1vbd5Z/
    • https://estesgroup.net/New-site-25062021/UkQPppHG9pLNE/
    • https://robointeligentedecomentarios.com/wp-includes/YBS9a02Y68auiEdP/
    • https://triclicks.net/wp-admin/bv/
    • https://thecanadianarab.com/wp-content/VJ/
    • 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
6dd9356952cdd6b95caf156e3e1c1471d7e098b9395e326c2a5a80643c35f018		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3546 bytes
xlm_sheet_01.xml
966e861f35410708893ffb1f97241504111fc93333012aa9c7613d379c3c60bb		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1204 bytes
xlm_sheet_02.xml
67d74ce6825b900ebce4400789acf68e409bb1eeffe279bee966d138d9d814c1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1227 bytes

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