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

Static analysis result for SHA-256 fdf74bf6a7201803…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-27 11:39:39 Authoring application: Microsoft Excel
MD5: 2a8376b25b86c50d70d194a1a7f7afa7 SHA-1: 7616dbe38397aaa717edbfb1239eadaaaf1d97b6 SHA-256: fdf74bf6a72018039aad27ffe2c9a13966aef86c3c0e45ad6862decc276b37a6
140 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro. This indicates an attempt to automatically execute code when the workbook is opened. The presence of dangerous formula APIs like RUN in the XLM macro sheet strongly suggests the macro is intended to download and execute 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
145f953a6b4c3912d3e8e14a94d3dcedfd78158db0b40ac0feaa38f0103612d1
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6598 bytes