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

Static analysis result for SHA-256 a5b085ab8fb0c399…

MALICIOUS

Office (OLE) / .XLS

182.5 KB Created: 2020-07-01 23:17:53 Authoring application: Microsoft Excel
MD5: d2dd670679bf058c5f1d54698c06a1ae SHA-1: 78da270912f7caf709bfe33b7b11f26c0b1c8b32 SHA-256: a5b085ab8fb0c399b94ee37ecd7770c3c54b41f5f3c430da6fae572c6c39f7bd
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1564.002 Hidden Files and Directories

The sample is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code upon opening the document. The macro sheet also employs environment evasion and a 'corrupt-close-decoy' to hinder analysis. The specific function `RUN` was identified as a dangerous API call within the Auto_Open macro, suggesting it likely attempts to execute an external payload.

Heuristics 4

  • 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.
  • XLM Auto_Open environment-evasion close gate critical OLE_XLM_ENVIRONMENT_EVASION_CLOSE
    Excel 4.0 macro sheet auto-executes environment checks with GET.WORKSPACE / GET.WINDOW, then shows a fake corruption/error message and closes the workbook when the host fails those checks. This is a malware sandbox-evasion pattern, even when the later payload stage is hidden behind obfuscated defined-name flow.
  • 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
60683e2e6ea03431fe7cee08d502253fcc6c98a06fa96df0f608e8199739c7b6		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 57869 bytes

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