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

Static analysis result for SHA-256 4a5ecb7048e7bb4f…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-27 11:43:40 Authoring application: Microsoft Excel
MD5: f37eb84cd93688adeef7d2a6d014bf62 SHA-1: 85aabc37e6c980d92bf48d11ac0635738665de65 SHA-256: 4a5ecb7048e7bb4f232d7116b2da3304fbbfb75b35ac777b433a27cffae3248f
140 Risk Score

Malware Insights

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

The sample contains Excel 4.0 (XLM) macro sheets, specifically triggering critical heuristics for the presence of an 'Auto_Open' defined name and the use of dangerous formula APIs like 'RUN'. This indicates the macro is designed to execute automatically upon opening the workbook. The presence of 'Auto_Open' suggests a malicious intent to run code, likely to download and execute a secondary payload, although the specific URL or command is not directly extractable from the provided evidence.

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
7318ecc84fe8a30090f01c6e85311210cbb8e4dada83200a2075703374eb1434
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6768 bytes