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

Static analysis result for SHA-256 7c7898e90623da90…

MALICIOUS

Office (OLE) / .XLSX

165.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 6657e88d05cc284b1a18b5a0db0bb9d4 SHA-1: 4fde4bdd8e71e4c8f1a6e80f79194b1c0dc267d1 SHA-256: 7c7898e90623da9078ce067a44f22e835a1666724f7c03f9f34c145c02ca9979
142 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. The macros utilize dangerous formula APIs, including functions like REGISTER and BIOLAFE, to download a payload from the URL http://artifkt.com/okmobi/certificate. This indicates a downloader or droppper functionality, aiming to execute a second-stage malicious file.

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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.iec.ch
    • http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#
    • http://ns.adobe.com/photoshop/1.0/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
bd262aef1b7122092a6dba2320a0d0734ca374097f0b62238d07ad999ce07250		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1994 bytes

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