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

Static analysis result for SHA-256 c766047027d57a15…

MALICIOUS

Office (OLE) / .XLS

149.5 KB Created: 2020-05-20 11:51:39 Authoring application: Microsoft Excel
MD5: 8d54d3ad2afaebfa7094c0f982c573f8 SHA-1: 5631a5636956ad8329ccebffbafbd3f0578415a2 SHA-256: c766047027d57a15cde8bd793412e123954e2f099dc9f257a601378d6d7669b1
140 Risk Score

Malware Insights

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

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros with auto-execution capabilities and the use of dangerous functions like RUN. The extracted macro code, though truncated, confirms the use of the RUN function, which is typically used to execute arbitrary commands. This strongly suggests the macro is designed to download and execute 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
7b748a7ce3780207703aaa42b17eaef32d12c7f6822238e040efabb76fceceba
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 39034 bytes