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

Static analysis result for SHA-256 329e2e9dadd6df6d…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:42:56 Authoring application: Microsoft Excel
MD5: 6c27de3a43981708aafa75ce62f40d71 SHA-1: 0c0a9a1e2b9d7a0dfb11f643e586aa14675a985a SHA-256: 329e2e9dadd6df6df6efd64cb44280df32fb12d1e0e606343c8e2bf8ec8fcb43
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The file is an Excel 4.0 macro-enabled workbook containing an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of dangerous formula APIs, specifically the RUN function, suggests the macro is designed to execute arbitrary commands. While the exact command executed by RUN is not fully recoverable from the provided evidence, its presence strongly indicates an initial stage of a malicious execution chain, likely for downloading and running a secondary 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
7b41e50e2800cffef05cfe566d81ba17adcd36edb4e8a5db286de02105a80909
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6429 bytes