High Severity

Attachment: PDF with JSFck obfuscation

Description

PDF attachment contains JavaScript obfuscated using JSFck encoding techniques. JSFck is a method of writing JavaScript code using only six characters: []()!+ which is often used to evade detection by security tools.

References

No references.

Sublime Security
Created Apr 22nd, 2026 • Last updated Apr 22nd, 2026
Source
type.inbound
and any(filter(attachments, .file_type == "pdf"),
        any(file.explode(.),
            .depth == 0
            and any(.scan.yara.matches,
                    .name in ("pdf_jsfck_strings", "pdf_jsfck_ratio")
            )
        )
)
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