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

Static analysis result for SHA-256 e9b90da35666899b…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:44:59 Authoring application: Microsoft Excel
MD5: 70ae1d5cbad0615a8605964ed63ebf90 SHA-1: b1a5091a55fc81c443958304588a9411e902f07d SHA-256: e9b90da35666899b2e8ae130daa93322149da75a4d68c96f4f6dbea18d9e368e
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 function, which is a known technique for executing malicious code upon opening the spreadsheet. The critical heuristic firings indicate the presence of dangerous formula APIs like RUN=0, suggesting the macro is designed to execute external commands. While no specific URLs or hashes were extracted, the presence of the Auto_Open macro strongly implies an intent 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
2314149f857c24d474f42ee7278115186c8d41c1aea4aef4b382416928397586
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6538 bytes