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

Static analysis result for SHA-256 d7fec88ac342d790…

MALICIOUS

Office (OLE) / .XLS

42.0 KB Created: 2020-11-12 14:56:49 Authoring application: Microsoft Excel
MD5: 6455c979c42ff2455c6c95c6a81813e5 SHA-1: 46bd90398d644a684632474164fe26f38b2e619c SHA-256: d7fec88ac342d790c3f8e1147d55cf2fdb922dacaaa54c5fd679f72c0f807f4d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel 4.0 (XLM) macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code when the workbook is opened. The macro sheet contains dangerous formula APIs, specifically the RUN function, which can be used to execute arbitrary commands. The document body is heavily obfuscated and contains no discernible user-facing content, suggesting its primary purpose is to deliver the malicious macro.

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
d753f341d73e8e3da88722f19e688c393dfb12655f1b53477026d1b29e4051a3
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9989 bytes