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

Static analysis result for SHA-256 5f2a1f32503df74b…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:39:50 Authoring application: Microsoft Excel
MD5: 4c80f70672b0696d53ad69a58b5b15e1 SHA-1: 8cecc761cb3162d0b423ebff080fb355790fb32e SHA-256: 5f2a1f32503df74b23c5086a9296a02d770c453701c491537a94466a308322d0
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 known technique for executing malicious code. The critical heuristics indicate the presence of dangerous formula APIs within the XLM macro, suggesting it's designed to run arbitrary commands. The macro's purpose is likely to download and execute a secondary payload, although no specific URLs or commands were directly extracted from the provided evidence.

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
151ddffa143f452a2a02e505ba832f5c33252f5c77d6a42605a345cd4c0a055c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6561 bytes