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

Static analysis result for SHA-256 782515014ad7fefd…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:38:50 Authoring application: Microsoft Excel
MD5: 021783191dd7b857665b97884c50a9e6 SHA-1: d6b2ec7b4997d6579482e618fe9aad186ebe2b93 SHA-256: 782515014ad7fefde55a0c8fb02afa7a426e659b449c72d3dccccda6e2752938
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 macros, specifically an Auto_Open entry. This indicates an attempt to automatically execute code when the file is opened. The presence of dangerous formula APIs in the Auto_Open macro suggests the execution of arbitrary code, likely to download and run 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
cd28e5d3d521cbf4fdcebb2f3f42071da224c1a25696de872231b56c53b3a9eb		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6868 bytes

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