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

Static analysis result for SHA-256 8800b7fd8e3b6b8e…

MALICIOUS

Office (OLE) / .XLS

103.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 94b8d6427ecda9366383fa9a14c5cf68 SHA-1: 64524ea55eebe3465f3365888a17da2381566529 SHA-256: 8800b7fd8e3b6b8e98c14bda53fbdfa5acfe041874345dc9b732f546fcce21c3
222 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros with an Auto_Open entry, indicating automatic execution upon opening. These macros are designed to download a file from the URL 'http://leyderompientes.cl/ywhbnizyl/555555555.png'. The presence of a lure to enable macros further supports a social engineering attack vector. The use of XLM macros and the download functionality points to a downloader malware.

Heuristics 6

  • 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.
  • URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime), across individual numeric cells (one ASCII charcode per cell), or split across multi-char fragment cells a download formula concatenates by reference (=A1&A2&… / CONCATENATE(...)). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries, LABELSST/RK/NUMBER cells, and FORMULA cell-reference concatenation in token order.
  • 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
  • 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://leyderompientes.cl/ywhbnizyl/555555555.png
    • http://leyderompientes.cl/ywhbnizyl/555555555.png�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a82429b91eed78633585de6f30576bde3ce168d8da53d45195b912247a514ea3		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2153 bytes

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