Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 fd4b117be86cb980…

MALICIOUS

Office (OOXML) / .XLSX

235.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-26
MD5: 3cada930974afca95ade7947ac2fbaee SHA-1: 0f71eab546495878adae640c227c673200dccce2 SHA-256: fd4b117be86cb9802e186c5b09a8618e3e17bbaa01695afea5f4ffead8999c0a
180 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros contain strings related to WinAPI functions like CreateDirectoryA and Kernel32, indicating attempts to interact with the operating system. The script also reconstructs URLs such as 'liketickets.com/fDjIGgWEQpk/DnvhnhO.png' and 'auto95.net/roDIBRTsXzJB/DnvhnhO.png', suggesting it downloads and executes a second-stage payload. The ClamAV detection explicitly names this as an Emotet downloader.

Heuristics 3

  • 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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • ClamAV: Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
f9ecd75a4ef00501f90e1d2a53644d2d8f7d2a7c02dc342dafa4abb13e82d5d1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 2898 bytes

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