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

Static analysis result for SHA-256 78cc610cbc414360…

MALICIOUS

Office (OLE) / .XLSX

318.0 KB Created: 2020-05-20 11:46:01 Authoring application: Microsoft Excel
MD5: 68678cf1d3a86bdf9a114758333be082 SHA-1: 18cf6e4822de94927d663d149daab5a06c74577d SHA-256: 78cc610cbc4143607424ed7b2db0baaab74ce54c7bec6a701158cc7c46e35e5d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The heuristics indicate an obfuscated execution chain, suggesting the macros are designed to run malicious code upon opening the spreadsheet. No specific family could be identified due to the generic nature of the macro execution.

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
d2f05ddb67afaf26bd07da4afebd33d3b49d8683c1b3aace8289637847922b9f
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 126252 bytes