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

Static analysis result for SHA-256 31e56bc28c033143…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:47:49 Authoring application: Microsoft Excel
MD5: c81218a2babe26069876e4603ae0c45d SHA-1: 6b568916eb11d212de6a7d6fac663be39c3026ff SHA-256: 31e56bc28c03314371d7807cd5a0fcfdf99d7bcec339fbcc8231f0e6d70c667b
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The heuristics indicate the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. While the specific commands or payloads are not directly visible due to truncation, the presence of Auto_Open strongly implies an initial stage of a malicious execution chain, likely for downloading and running a second-stage 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
6a45b963e732bea023efd6d930da73d5e52afab37e848f096b7fdca917043d61
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6735 bytes