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

Static analysis result for SHA-256 be79799e584cfeac…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:25 Authoring application: Microsoft Excel First seen: 2023-03-30
MD5: 95b76e54f8af81a0e045ca25a3190633 SHA-1: 2aa41013eb9ee260563341eb79a860737e495546 SHA-256: be79799e584cfeac364c9bdbdcae57e05fb4c94bf59886e3325efd1bdd9302cc
140 Risk Score

Malware Insights

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

The critical heuristics indicate the presence of Excel 4.0 macros, specifically an Auto_Open defined name, which is a known method for automatic execution upon opening the workbook. The `RUN=0` in the heuristic suggests the macro is configured to execute a command, likely a downloader or initial execution stage. The extensive obfuscated text in the DOC BODY further supports the malicious intent, though its exact purpose cannot be determined without deobfuscation.

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
8a87b52118cb6a9d66d9b00faa464477e589d6248da95d3afff77c94972e4358
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6533 bytes