Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 5d31e83b1dda43ba…

MALICIOUS

Office (OOXML) / .XLSX

46.6 KB Authoring application: Microsoft Excel 16.0300 First seen: 2022-11-02
MD5: cb4e59e39a6eef5b8752681b6f871e56 SHA-1: ebe9658d642bfafc88bf21a48e8eb455066d6926 SHA-256: 5d31e83b1dda43ba478dbf1bbd5b1ab90021810860493110ac6175f69e58a93d
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET and OOXML_XLM_AUTOOPEN_DEFINEDNAME heuristics. The macros utilize dangerous XLM functions like FORMULA to download payloads from multiple URLs, including 'http://eles-tech.com/css/KzMysMqFMs/'. The ClamAV detection as 'Xls.Downloader.Emotet-b600c9ff3ec1c136-9950239-0' strongly suggests the Emotet family. The macros appear to construct commands to download and execute a file named '..\xewn.dll' or 'r"&"egsv"&"r"&"32.exe'.

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.Emotet-b600c9ff3ec1c136-9950239-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b600c9ff3ec1c136-9950239-0
  • 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 http://eles-tech.com/css/KzMysMqFMs/
    • https://txpcrescue.com/cgi-bin/5tSO8/
    • http://haribuilders.com/zoombox-master/4HYGX/
    • http://gonorthhalifax.com/wp-content/yTmYyLbTKZV2czsUO/
    • http://hadramout21.com/jetpack-temp/Py/
    • http://hansen-arnal.com/cp/iiTrAeEtvOwmjjekWgI/
    • 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
4153191ccbeaead436d640cd9bad7b4c39fa54474c8ec9a17be8e3e4600146ed		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3602 bytes

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