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

Static analysis result for SHA-256 a398d12ee9a893c9…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:44:58 Authoring application: Microsoft Excel
MD5: cf319b981b762e02d0269c95eaf1b432 SHA-1: b7de493ebd1abd878c341fd128ee3b41b103ac74 SHA-256: a398d12ee9a893c9bd4f639735616a6e4e80af8884630a3e64c6c15f9269b01c
140 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 (XLM) macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristic firings. The presence of an 'Auto_Open' defined name suggests that the macro will execute automatically upon opening the workbook. The 'RUN' function API is flagged as dangerous, implying the macro is capable of executing arbitrary commands, likely to download and execute a second-stage payload. No specific family could be identified.

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
6d4095b0dcc777fb969c469481da1376602ae1b734317e2fb80096b5153a4f03
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6774 bytes