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

Static analysis result for SHA-256 ad58610fbe539092…

MALICIOUS

Office (OLE) / .XLSX

41.5 KB Created: 2020-11-13 16:10:17 Authoring application: Microsoft Excel
MD5: 88546007d35c16dd255754eea62960d1 SHA-1: 0bf7ab72d8e1a43553e0f29aba600a602ab5585b SHA-256: ad58610fbe53909228697d9d12cc06c47c5f4ad053537779ee478fe25e6607f4
140 Risk Score

Malware Insights

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

The critical heuristic OLE_XLM_DANGEROUS_FN indicates the presence of an Excel 4.0 macro sheet with a dangerous formula API, specifically the RUN function, which is often used to execute arbitrary commands. The Auto_Open defined name further confirms that this macro will execute automatically upon opening the workbook. While no specific URLs or hashes were extracted, the presence of these dangerous functions strongly suggests the macro's intent is 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
4c9ead4cec2faa9837bc8758ccf7b793ff0c881fb36eb5ba707f70c0e602cf2b
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9591 bytes