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

Static analysis result for SHA-256 faddb41690e2a06a…

MALICIOUS

Office (OLE) / .XLSX

284.0 KB Created: 2020-11-20 17:59:00 Authoring application: Microsoft Excel
MD5: c372f4d67f99c3e807be8e424890a131 SHA-1: 49bfb9b5d6b4f14a0023710bc37d13d3a9eaa9dd SHA-256: faddb41690e2a06a400248d03aebc186f54cc62f522e54c21e482d7bd165c720
148 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The sample contains Excel 4.0 macros, including an Auto_Open entry, which is a strong indicator of malicious intent. The script attempts to execute a command that downloads and saves a file named 'bc.exe' from the URL 'https://tinyurl.com/y9z6zzxj'. The VBA project does not contain executable statements, but the XLM macros are the primary mechanism for execution. The confidence is slightly reduced due to the obfuscated nature of the XLM macro execution command.

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.
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
39c7496fc1421c7fa4d4f8a8493d77b5ffd1f872f2afd75c66058a373e7c9733		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2264 bytes
macros.bas
fed365d3401536fb63e11d0a36cc7c35338c0a8c74a96fb254c46366ad6287cd		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 642 bytes

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