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

Static analysis result for SHA-256 f3a1ff4773ea210a…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:45:23 Authoring application: Microsoft Excel
MD5: 6639a539b272cfa30b68e9505cdb0698 SHA-1: 3da68ad66195f25b3bb99c6261e8494ea8161cd4 SHA-256: f3a1ff4773ea210ae384d33b80bfa9dc45e17eec69f16c6f492eae33c92f196f
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The heuristics indicate the presence of dangerous formula APIs within the macro, including the RUN function, suggesting the macro is designed to execute arbitrary commands. The document body contains a large amount of seemingly random text, which is typical for obfuscation or to pad the file. No specific URLs or hashes were extracted, but the Auto_Open macro is the primary indicator of malicious intent, likely 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
72769adf770e9e1d29144f580255240fd9bef43be59cfafc908c823f520cae10
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6774 bytes