Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 f9f64e6bdc002830…

MALICIOUS

Office (OLE) / .XLS

115.6 KB Created: 2022-01-24 20:48:09 Authoring application: Microsoft Excel
MD5: 095db5edc2fd8eae0a8272dc67be86f0 SHA-1: ffeb26a27c01d28dcfa1c6ddd71ff35e32e860e7 SHA-256: f9f64e6bdc0028301382991b2fb37308ebb55e46b64a56433decec98fa3c3346
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV with the signature Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open function that utilizes dangerous formula APIs like RUN. This indicates the macro is designed to execute arbitrary commands, likely to download and run a second-stage payload, consistent with Emotet downloader behavior.

Heuristics 4

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • ClamAV: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
5a0137a4ff8036cfa03ad914b464e95f104474d870faad94ec8edd89262cb0e9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 5174 bytes

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