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

Static analysis result for SHA-256 18a2fa4448b535dc…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:38:36 Authoring application: Microsoft Excel
MD5: 2e454bfb7040d2544e1905ad0c536c22 SHA-1: 63e15fb9a1b1d92b3877e021c54ad2a0ea060d3c SHA-256: 18a2fa4448b535dc4308ee794812744f3f096327e70848e3ae9a5c2ba556a06d
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening the workbook. The presence of dangerous formula APIs in the Auto_Open macro indicates a high likelihood of malicious intent, likely to download and execute a second-stage payload.

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
e70818d910a82395187d323d30da097ec834855c53c91a35f1760e00807a2aa7		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6727 bytes

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