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

Static analysis result for SHA-256 7f9cc5857cb833d7…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:44:26 Authoring application: Microsoft Excel
MD5: 99d9d559148766d5bf930cb59d714c06 SHA-1: cb2eae39172fe78764eb3c7365b70c8b40de3993 SHA-256: 7f9cc5857cb833d79b1a525d2b728c6256290e67b29509554f531ea2442f185a
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a critical finding indicating potential malicious execution. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary code. This functionality is commonly used to download and execute further malicious payloads, hence the classification as an unknown family macro-based downloader.

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
506ea3ac31227d0d8f432ea62cdea220d26a1c2b106899a22ec65b59bbd56ec2
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6762 bytes