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

Static analysis result for SHA-256 91cfbcd88ed67af8…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:42:29 Authoring application: Microsoft Excel
MD5: ee971040ad438bcba2d8a4312aad0f4a SHA-1: 2e028ddbdf81d307010e0d6fb76afa0dda98a7a0 SHA-256: 91cfbcd88ed67af8b62c8cb60f3f2a9c1374929e2f61a741bfb47f32633fe81e
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 (XLM) macro sheets, specifically triggering the 'Auto_Open' function. This indicates the workbook is designed to automatically execute code upon opening. The critical heuristic 'OLE_XLM_DANGEROUS_FN' with 'RUN=0' strongly suggests the macro attempts to run an external program or script. While no specific URLs or hashes were extracted, the presence of the Auto_Open macro and the dangerous function usage points to a downloader or initial execution stage for a malicious 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
466689db0f7506065d7c031957c3c82e320a7be3996131911d2753017f1894e3
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6531 bytes