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

Static analysis result for SHA-256 b7e1d9ac63ddc51d…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:38:15 Authoring application: Microsoft Excel
MD5: 7cb5f58955bd39f5c32cf251c16ae401 SHA-1: 5d84f78e4dcb467a9095054f9ea8eed962475294 SHA-256: b7e1d9ac63ddc51db095025cdf35cc31a040e138b41ff7e0fca7e12c9884cd51
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 critical heuristics for an Auto_Open defined name and the use of dangerous formula APIs like RUN. The presence of the Auto_Open macro indicates that arbitrary code execution is intended upon opening the workbook. The macro sheet also contains a large amount of obfuscated data, suggesting it is designed to hide malicious commands. The 'RUN' function is a critical indicator of an attempt to execute external commands.

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
207742084f879dc3ca8fbb6807ff9199b7dba7b84fd81b4299271c4a61d8338e
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6433 bytes