Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 766920a9610d2ddc…

MALICIOUS

Office (OLE) / .XLSX

95.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-07-12
MD5: 06c86ab748726b11f8cda25ac95101a6 SHA-1: 6baebca15537c07a24d6e1d8bbaa88b09863e02e SHA-256: 766920a9610d2ddceacc45cbf6205dae8e63dbaf8f0bd194d375197053570594
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. ClamAV identified the sample as Emotet, a downloader family. The presence of the Auto_Open macro indicates the file is designed to automatically run a payload upon opening, likely to download and execute a second-stage threat.

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-ea81817e7f807ab1-9952142-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-ea81817e7f807ab1-9952142-0
  • 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
168e7c20400a87ec53e7f85fc05780d92d7341ae7fdc256e3891ea4b48ec5adc		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8132 bytes

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