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

Static analysis result for SHA-256 abcc20de65aa3eeb…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:28:02 Authoring application: Microsoft Excel
MD5: 92cc9d1ec7c7d5fd079dc099e5c3eaea SHA-1: 431a48d14dada770ce0c3057901d9897a4bd721c SHA-256: abcc20de65aa3eebd908035395ecc84f934d69497c5eae64df3696146ab6c816
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

The file contains Excel 4.0 (XLM) macro sheets, specifically triggering the Auto_Open defined name heuristic. This indicates the workbook is configured to automatically execute a macro upon opening. The presence of dangerous formula APIs like RUN further confirms the intent to execute arbitrary code. While the specific payload is not directly visible, the Auto_Open function is a common method for initial stage malware delivery, often downloading and executing 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
7dea3878d9e3a7777dc6b58cbb2175f457ea7caf58c129b05a8a317b72e3900a
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6629 bytes