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

Static analysis result for SHA-256 2c96165b001331cb…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-27 10:22:30 Authoring application: Microsoft Excel
MD5: 78153d222cf7e18d38d2d368afa0fbc3 SHA-1: 18983b3f51ecffa040f61c824ee21cdc1b40ce1b SHA-256: 2c96165b001331cb08d6078de67c4fc13ee5bdee5cc93860ed7f0e9da10a5d31
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 that utilizes dangerous functions, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands. The macro sheet is named 'ZvXHArTAaW', which is likely a placeholder or part of the obfuscation. The primary attack pattern is the execution of a malicious macro to download and run a secondary payload.

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
63ec96cfa1744e2193d6f9f0a18cfa3fd629fb2ab2aab459e36599bab73aad30
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6836 bytes