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

Static analysis result for SHA-256 f31e8f97295655b4…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-27 11:38:47 Authoring application: Microsoft Excel
MD5: 4358a9ad06b40f739a7b804ff3ab6ab5 SHA-1: 91164b01647edf8e6dc76629760badf2263d5eb5 SHA-256: f31e8f97295655b4346b617c631d74930d42f336dc1c0f9e67a3cb537d37330b
140 Risk Score

Malware Insights

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

The sample is an Excel 4.0 (XLM) 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 second-stage payload. The document body contains heavily obfuscated and truncated text, making it difficult to determine the exact lure, but the macro execution is the primary threat.

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
b6f845bd4aa2a6221d0ca2f1f28ff9af7ef619f930905305de30c338963550af
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6767 bytes