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

Static analysis result for SHA-256 05c1cc24508fafe6…

MALICIOUS

Office (OLE) / .XLS

469.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 7f82c7bfbb002ebb4f48580be9cb1429 SHA-1: ef59f7aaf99a3e9c6976304df81534130f688b8b SHA-256: 05c1cc24508fafe66b32db07e2d31818f8a40c1b64e5901a84c8514b7522dab6
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a known technique for executing malicious code. The macro sheet contains a reference to a URL, suggesting it is designed to download and execute a second-stage payload. The Auto_Open entry directly calls the RUN function, which is a dangerous API for executing arbitrary code.

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
877b24336da75137a3a99cda7752c4a2d3bef2725374cfe3b531d5b368960619		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 14228 bytes

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