Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 970035848bd05638…

MALICIOUS

Office (OLE) / .XLS

73.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-16
MD5: c149300a5b6a8fb3b5462f15f9238003 SHA-1: 0bb1b741677652f60baec74993fae5843cdeb655 SHA-256: 970035848bd05638b3e4defb67bd1659bbcf4b9e5ef1010d6a06cc7f76b6ba76
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro that uses dangerous functions, specifically the RUN function. The macro constructs several URLs by concatenating strings, which are likely used to download and execute a second-stage payload. The ClamAV detection explicitly names this as an Emotet downloader.

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-ea85857e7e81817a-9950241-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-ea85857e7e81817a-9950241-0
  • 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
9aad8521d90ca7f536d86e805137dbff97d82a2ac842ee968dd491451c1e0d83
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6831 bytes