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

Static analysis result for SHA-256 887787a1045048b7…

MALICIOUS

Office (OLE) / .XLS

41.5 KB Created: 2020-11-13 16:12:53 Authoring application: Microsoft Excel
MD5: 7d720d28d4c3ee8fc9710bec67b3f53d SHA-1: c6120a91ff9466bd379b252a624c106e38c3b544 SHA-256: 887787a1045048b782c6c60fe1ae3337dec7785162d5329ab0d319e68c8771e9
140 Risk Score

Malware Insights

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a common method for executing malicious code upon opening the spreadsheet. The macro sheet contains dangerous formula APIs, including a RUN function, suggesting it is designed to download and execute a secondary payload. No specific family could be identified.

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
0ef2f510d1bb15c6604fa8c8f128f08bdeb674a21849f99638f6a51d04d10875		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9404 bytes

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