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

Static analysis result for SHA-256 9b7f305755a0bd70…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:35:34 Authoring application: Microsoft Excel
MD5: 3602164734d9f03ef7cf0d6182a6e423 SHA-1: 8124aed798e4670f02c377fc935456b9970a5c62 SHA-256: 9b7f305755a0bd70184bfd3f59d6c7f654c588e7ea04cfe8fb35954af2c643f1
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates the workbook is configured to automatically execute a macro when opened. The presence of dangerous formula APIs like RUN further suggests the macro is intended to execute arbitrary commands, likely to download and run a second-stage payload. The document body contains heavily obfuscated text, which is typical for lures in macro-based attacks.

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
f119d11e19d4676aa6d808ca1848f26a36752649eb60b2fadc5f7671b90951d4
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6649 bytes