Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 0b670cebfcd68687…

MALICIOUS

Office (OOXML) / .XLSM

75.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-14
MD5: b337e2d665772332884fbeb83afb3ee6 SHA-1: d8b8ef9bcd3b9694ecd4c143d70233033e4c6f78 SHA-256: 0b670cebfcd686873ce2ad5031cc824f1c26f88f4d0a3b244e07a6f5c7c37ddb
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an XLSM document containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous formula APIs like FORMULA to download and execute payloads. The ClamAV signature specifically identifies it as an Emotet downloader. The macros construct URLs by concatenating strings, such as 'https://aliceefan.com/wp-content/dTDBJDMSb/', which are used to fetch the next stage of the attack.

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.Emotet03220-9941786-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941786-0
  • 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 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
26edf9bacfee50b5986426c79eb3159c595a38f59b61b257c6666d6dbea79cdc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3854 bytes
xlm_sheet_01.xml
16728df0c83af9edbca13e7bf934528980971291f8afa9e213237ad5e9c550aa		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1275 bytes
xlm_sheet_02.xml
eb62ea8fd79da591769622356698b97ab3294ef8032cb3ffcd8f29cb5968841e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1213 bytes

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