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

Static analysis result for SHA-256 b4cd36f70236cb33…

MALICIOUS

Office (OLE) / .XLSX

52.5 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: 1b09ac08e88dca6c45f20201f473c325 SHA-1: e42ac5dc78cc1d4a7c212a9eab317395f0c95adf SHA-256: b4cd36f70236cb33af3fb7f64c838182f3b65d918a2640f5839c8f57551daccb
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. The macro uses the `REGISTER` function, indicating it's designed to load external functions, and the `RUN` function, which is a dangerous API call used to execute arbitrary commands. The macro attempts to download a payload from the URL `http://parosdiving.com/catsdeal/color.php`. The presence of a macro-enable lure further supports the malicious intent.

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.
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a86dec99e2013db52fcb6c6382b9017e3956457f0a39ff5efd1f9ebf10b6deee
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2321 bytes