在生成的数据中检查和不打印javascript?

如果您不反对外部依赖项,则 HTML Purifier library 对于大多数xss攻击来说是一个很好的过滤器。

不完全是一种标准的方式;因为如果你正在做: <img src="${path}"> 和 ${path} 扩展到 http://p0wned.com/jpg.jpg" /><script src="p0wned.com/js.js"/>

不管怎样,我喜欢这个正则表达式:

#from http://www.perlmonks.org/?node_id=161281
sub untag {
  local $_ = $_[0] || $_;
# ALGORITHM:
#   find < ,
#       comment <!-- ... -->,
#       or comment <? ... ?> ,
#       or one of the start tags which require correspond
#           end tag plus all to end tag
#       or if \s or ="
#           then skip to next "
#           else [^>]
#   >
  s{
    <               # open tag
    (?:             # open group (A)
      (!--) |       #   comment (1) or
      (\?) |        #   another comment (2) or
      (?i:          #   open group (B) for /i
        ( TITLE  |  #     one of start tags
          SCRIPT |  #     for which
          APPLET |  #     must be skipped
          OBJECT |  #     all content
          STYLE     #     to correspond
        )           #     end tag (3)
      ) |           #   close group (B), or
      ([!/A-Za-z])  #   one of these chars, remember in (4)
    )               # close group (A)
    (?(4)           # if previous case is (4)
      (?:           #   open group (C)
        (?!         #     and next is not : (D)
          [\s=]     #       \s or "="
          ["`']     #       with open quotes
        )           #     close (D)
        [^>] |      #     and not close tag or
        [\s=]       #     \s or "=" with
        `[^`]*` |   #     something in quotes ` or
        [\s=]       #     \s or "=" with
        '[^']*' |   #     something in quotes ' or
        [\s=]       #     \s or "=" with
        "[^"]*"     #     something in quotes "
      )*            #   repeat (C) 0 or more times
    |               # else (if previous case is not (4))
      .*?           #   minimum of any chars
    )               # end if previous char is (4)
    (?(1)           # if comment (1)
      (?<=--)       #   wait for "--"
    )               # end if comment (1)
    (?(2)           # if another comment (2)
      (?<=\?)       #   wait for "?"
    )               # end if another comment (2)
    (?(3)           # if one of tags-containers (3)
      </            #   wait for end
      (?i:\3)       #   of this tag
      (?:\s[^>]*)?  #   skip junk to ">"
    )               # end if (3)
    >               # tag closed
   }{}gsx;          # STRIP THIS TAG
  return $_ ? $_ : "";
}

在php中,我将从strip_标记开始。像这样:

$output = strip_tags($input);

如果我想在用户输入中允许一些标记,我会将它们包括在内,如下所示:

$output = strip_tags($input, '<code><em><strong>');

我认为不可能找到这样的javascript代码。

您必须通过某种类型的解释器传递数据,以试图找到有效的js语句。这将是非常处理器密集型的,可能会根据文本的性质产生许多误报。

实体转义元字符可能是进一步保护应用程序免受筛选器可能错过的攻击的最佳方法。如果javascript作为常规文本加载,则无法运行。