Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 ef89dd7f4fbf4d08…

MALICIOUS

Office (OLE)

36.5 KB Created: 2020-11-25 10:38:51 Authoring application: Microsoft Excel
MD5: 87504f56a0ccca5edf1bbaa00c7ba6f3 SHA-1: 5162baa9ddb5d7735a3131e69063cc71de23ddc0 SHA-256: ef89dd7f4fbf4d080b5fb9e5dbe664699f3d7b04c9f17ca2dff1cef3dd6154d8
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 defined name, which is a critical finding indicating potential automatic execution of malicious code upon opening the workbook. The presence of dangerous formula APIs further increases the risk. While the exact payload is not discernible from the provided evidence, the mechanism points to a macro-based execution of 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
cff792c2c6dc6714858bc8eff1d1d3a9c37480a16b242e3ea0a3e29f9d01b284		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6426 bytes

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