Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 8ca9b9b8bfbba28a…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-25 10:45:39 Authoring application: Microsoft Excel First seen: 2022-04-27
MD5: 5078cf912a2f131211c92ab8246d1ff9 SHA-1: 49e6a91bb95021ac2d7c6b6327c09305ba1a9829 SHA-256: 8ca9b9b8bfbba28aa8a680257f5bb9c596eb08a9f8a16d32f1020c0fa5d04874
140 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro and the use of dangerous formula APIs, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands, likely to download and execute a secondary payload. The document body contains heavily obfuscated text, further indicating malicious intent.

Heuristics 3

  • 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.
  • 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
c44a58622ba53ea261afc0ca970687afc6865ff5e3c9d47748e24b4262c17bed
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6402 bytes