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

Static analysis result for SHA-256 49dc71dc059c1a11…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:36:07 Authoring application: Microsoft Excel
MD5: ae1463272ec40495ef9444a4258f5dfc SHA-1: 546bf8295c8a62f632f8e8fbc2f2038edd873b98 SHA-256: 49dc71dc059c1a11ff602513b28d813fc76d95559bc2a5ade96a43e3b67c2c88
140 Risk Score

Malware Insights

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

The critical heuristic OLE_XLM_DANGEROUS_FN indicates the presence of dangerous formula APIs within an Excel 4.0 macro sheet, specifically the RUN function. This strongly suggests the macro is designed to execute arbitrary commands. The presence of an Auto_Open defined name further confirms that this malicious macro will execute automatically upon opening the workbook. While no specific URLs or hashes were extracted, the core functionality points to a downloader or initial execution stage.

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
1268d818366371d868d8eb0c4c71f7f5811abe006208fc438eebeb33633f8398
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6618 bytes