Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 8ff31d0987897243…

MALICIOUS

Office (OLE) / .XLS

114.7 KB Created: 2022-01-24 01:40:11 Authoring application: Microsoft Excel
MD5: dfa4bc7bea74fb143ad48540feb8835c SHA-1: 3edb0c5778d5e01775a503b2d90c87b57db82cb8 SHA-256: 8ff31d09878972431605d02cdf0d112661fc4cf8402ba68a5de1b4f431044f18
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The sample is identified as malicious by ClamAV with the signature Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0. Critical heuristics indicate the presence of Excel 4.0 macros, specifically an Auto_Open function that utilizes dangerous formula APIs like RUN. This strongly suggests the macro is designed to download and execute a second-stage payload, a common characteristic of Emotet.

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
86637063ac2c97bbefdbc9033f21cd30e9484ed274aba63ad50d62dfa1de93cd
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4341 bytes