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

Static analysis result for SHA-256 525522884562954f…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:07 Authoring application: Microsoft Excel
MD5: bf0f4a1e67dc27289b6e5a70ea369a31 SHA-1: b9b8b9e5d316513acf85065618b961b4b05ee3fa SHA-256: 525522884562954f27ba9c14ba53c5dd94e3a04be3d62f7844d8c14603b796e5
140 Risk Score

Malware Insights

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

The critical heuristic firings indicate the presence of Excel 4.0 macros with an Auto_Open function, which is a known technique for executing malicious code. The `RUN=0` formula API within the Auto_Open macro suggests an attempt to execute an external command or payload. While the document body contains a large amount of seemingly random text, the macro sheet itself is the primary indicator of malicious intent, pointing towards 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
7bf6fd8e0bcda814bedce5c573e3fb63f74b9aefa0d101c07ccffa6933aded13
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6479 bytes