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

Static analysis result for SHA-256 5a914f2c32cba075…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:45:34 Authoring application: Microsoft Excel
MD5: 7b22b87d54abd24639ecb78ce6c25bc6 SHA-1: c648eac5f4760f129ce0c80b1eda5c02f753e88b SHA-256: 5a914f2c32cba075801246d936e173d54e7b1b9aad886427ab98358f8acae6bf
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 (XLM) macros, specifically an Auto_Open macro. This indicates an attempt to automatically execute code when the document is opened. The presence of dangerous formula APIs like RUN suggests the macro is intended to download and execute a second-stage payload, a common technique for malware delivery.

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
8fe5ea5f69549c16c9eee91a41cdc6e4483a3bc54766e3636c71a00a856b8f7b		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6845 bytes

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