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

Static analysis result for SHA-256 4b5f3f441502c304…

MALICIOUS

Office (OLE) / .XLS

96.5 KB Created: 2020-05-24 21:15:18 Authoring application: Microsoft Excel
MD5: bf2d6594430834917ec9e2ef04758c67 SHA-1: f8c7c90620d2448a50bae8fefea85d7ba5919eb7 SHA-256: 4b5f3f441502c30485fb49e5e1877a3aeb7cee6ddb39c509f78119ba26860563
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros designed to auto-execute. The macro sheet contains a reconstructed URL, 'http://gsa.lobcmurizex.com/F', which is likely used to download and execute a second-stage payload. The use of XLM macros and a suspicious URL points to a downloader or droppper functionality.

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
e2ce912edac73eff38945c9843f49298846ead6c625e2afb460350bc2bf9099c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 73382 bytes

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