Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 d691645cdaef8f04…

MALICIOUS

Office (OLE) / .XLS

95.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-07-08
MD5: 567e78dc543e406e3b2c2eec82a4d66b SHA-1: 9dec5ae8152593df4ca690385456ab776dc0fcb6 SHA-256: d691645cdaef8f04850ad99dc522a9c879c99a8878e5a47fdb8a79da50af29f9
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: Malicious File

The file is an Excel 4.0 macro-enabled workbook detected as Emotet by ClamAV. The critical heuristics indicate the presence of an Auto_Open macro that uses dangerous formula APIs, specifically the RUN function, which is commonly used to download and execute secondary payloads. The macro sheet itself contains obfuscated strings that likely form the URL or command for the payload.

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
98f1ff2f8ad02f615407af2b43d3cce9fda2c4449c93c2eb92d1085006ba4331
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8144 bytes