Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 e2b69f01654db58e…

MALICIOUS

Office (OOXML) / .XLSX

1.16 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-20
MD5: 38be6b127ea2ab68eb982eb794dcb5b2 SHA-1: ef46728ddc720318ae763f37e4733cdec409e89d SHA-256: e2b69f01654db58eee0c79f84441fae7154c685305332e03801efe1c5e89f9aa
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample is an Excel file containing Excel 4.0 macros. These macros utilize WinAPI calls such as CreateDirectoryA to create a directory named 'C:\Jhfrg'. Subsequently, they use 'regsvr32' to download and execute files into the created directory, specifically referencing 'C:\Jhfrg\Rgsrhda.ooocxx', 'C:\Jhfrg\Rgsrhdb.ooocxx', and 'C:\Jhfrg\Rgsrhdc.ooocxx'. This behavior is characteristic of Emotet's downloader functionality, which aims to fetch and execute further malicious payloads.

Heuristics 4

  • 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
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
91be447cf4ed5b5fa18315c6180ef6d62647686972b570319f960439fe37d717		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject3.bin 3099136 bytes
ooxml_oleobject_00_ole10native_00.bin
a6724425b761391a2288cdb0e402bdc8cf2de9a4e93260c95af92b78344a367e		 ole-package OOXML xl/embeddings/oleObject3.bin Ole10Native stream: Ole10Native 3072068 bytes
emf_00.emf
3f0f6bb70f3d65dcc8d248d78ac320bcc22b1148ea5fdd2c1043065d03460133		 ooxml-emf OOXML EMF part: xl/media/image1.emf 6144552 bytes
xlm_sheet_00.bin
69a2e1d9485c0dfa0a658594ddc6d39e897b39125ece8f4c2b2985736ffbc1c7		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 2137 bytes

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