Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 7a28319e85687096…

MALICIOUS

Office (OOXML) / .XLSX

92.0 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 12.0000
MD5: 735e0364ab96dd0e21a77f451aac80da SHA-1: 4eb89858551687e7281e6ff38d9d419c239cbb57 SHA-256: 7a28319e85687096877903530061e4652a4435bfd14caeb546419af79b2aac4a
260 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1059 Command and Scripting Interpreter

The sample contains a Workbook_Open macro that executes obfuscated VBA code. This code utilizes CreateObject to call shell execution functions, indicating an attempt to download and run a second-stage payload. The ClamAV detection name 'Xls.Downloader.EmotetRed02221-9938910-0' strongly suggests the Emotet family and a downloader functionality.

Heuristics 6

  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • ClamAV: Xls.Downloader.EmotetRed02221-9938910-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetRed02221-9938910-0
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
de7bcbc45ff0a77d05d9af662bacc316e71be11a980e94f6673e556a5dd9d1bc		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 12808 bytes
vbaProject_00.bin
aa9943a3a346e953a510f1ad9a2ae053c0808ef011dc86b6f43e9e3d8a14fb16		 vba-project OOXML VBA project: xl/vbaProject.bin 37888 bytes

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