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

Static analysis result for SHA-256 30f265f905dcf840…

MALICIOUS

Office (OLE) / .XLSX

235.5 KB Created: 2020-05-21 08:21:12 Authoring application: Microsoft Excel
MD5: 6f7112f5bd2a70d3b94bc5521f4267b5 SHA-1: 3070f2f9b5506001551535a50c2ca03e1265b588 SHA-256: 30f265f905dcf84030c91e842caebcfbe1869aeed3ec4f6d240165f128bf7559
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel spreadsheet containing obfuscated Excel 4.0 (XLM) macros. The critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for automatic execution upon opening the document. The obfuscated nature of the Auto_Open execution chain suggests malicious intent, likely to download and execute a secondary payload. No specific IOCs like URLs or file hashes were extracted from the macro content itself.

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.
  • Obfuscated XLM Auto_Open execution chain critical OLE_XLM_OBFUSCATED_AUTOEXEC_CHAIN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and an obfuscated formula execution chain. The macro builds strings through FORMULA(CHAR(...)), primes state with SET.VALUE / GET.CELL / GOTO, and transfers control through RUN(). This is a high-confidence XLM malware pattern.
  • 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
f250e8c3de2e3fbfa5a4f4e25c60ea48f4ae98039e78b51d50b1a73f5c16aebe
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 128613 bytes