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Fix XSS
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joeldrapper committed Apr 16, 2024
1 parent 1b59ab3 commit 9e3f5b9
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Showing 2 changed files with 73 additions and 1 deletion.
2 changes: 1 addition & 1 deletion lib/phlex/sgml.rb
Expand Up @@ -382,7 +382,7 @@ def __attributes__(attributes, buffer = +"")
end

lower_name = name.downcase
next if lower_name == "href" && v.start_with?(/\s*javascript:/i)
next if lower_name == "href" && v.to_s.downcase.tr("\t \n", "").start_with?("javascript:")

# Detect unsafe attribute names. Attribute names are considered unsafe if they match an event attribute or include unsafe characters.
if HTML::EVENT_ATTRIBUTES.include?(lower_name) || name.match?(/[<>&"']/)
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72 changes: 72 additions & 0 deletions test/phlex/view/naughty_business.rb
Expand Up @@ -85,6 +85,78 @@ def view_template
end
end

with "naughty javascript link protocol with a hidden tab character" do
view do
def view_template
a(href: "\tjavascript:alert(1)") { "XSS" }
a(href: "j\tavascript:alert(1)") { "XSS" }
a(href: "ja\tvascript:alert(1)") { "XSS" }
a(href: "jav\tascript:alert(1)") { "XSS" }
a(href: "java\tscript:alert(1)") { "XSS" }
a(href: "javas\tcript:alert(1)") { "XSS" }
a(href: "javasc\tript:alert(1)") { "XSS" }
a(href: "javascr\tipt:alert(1)") { "XSS" }
a(href: "javascri\tpt:alert(1)") { "XSS" }
a(href: "javascrip\tt:alert(1)") { "XSS" }
a(href: "javascript\t:alert(1)") { "XSS" }
a(href: "javascript:\talert(1)") { "XSS" }
end
end

it "strips the javascript protocol" do
expect(output.scan("<a>").size).to be == 12
expect(output.scan("href").size).to be == 0
end
end

with "naughty javascript link protocol with a hidden newline character" do
view do
def view_template
a(href: "\njavascript:alert(1)") { "XSS" }
a(href: "j\navascript:alert(1)") { "XSS" }
a(href: "ja\nvascript:alert(1)") { "XSS" }
a(href: "jav\nascript:alert(1)") { "XSS" }
a(href: "java\nscript:alert(1)") { "XSS" }
a(href: "javas\ncript:alert(1)") { "XSS" }
a(href: "javasc\nript:alert(1)") { "XSS" }
a(href: "javascr\nipt:alert(1)") { "XSS" }
a(href: "javascri\npt:alert(1)") { "XSS" }
a(href: "javascrip\nt:alert(1)") { "XSS" }
a(href: "javascript\n:alert(1)") { "XSS" }
a(href: "javascript:\nalert(1)") { "XSS" }
end
end

it "strips the javascript protocol" do
expect(output.scan("<a>").size).to be == 12
expect(output.scan("href").size).to be == 0
end
end

with "naughty javascript link protocol with a hidden whitespace character" do
view do
def view_template
a(href: " javascript:alert(1)") { "XSS" }
a(href: "j avascript:alert(1)") { "XSS" }
a(href: "ja vascript:alert(1)") { "XSS" }
a(href: "jav ascript:alert(1)") { "XSS" }
a(href: "java script:alert(1)") { "XSS" }
a(href: "javas cript:alert(1)") { "XSS" }
a(href: "javasc ript:alert(1)") { "XSS" }
a(href: "javascr ipt:alert(1)") { "XSS" }
a(href: "javascri pt:alert(1)") { "XSS" }
a(href: "javascrip t:alert(1)") { "XSS" }
a(href: "javascript :alert(1)") { "XSS" }
a(href: "javascript: alert(1)") { "XSS" }
end
end

it "strips the javascript protocol" do
expect(output.scan("<a>").size).to be == 12
expect(output.scan("href").size).to be == 0
end
end

Phlex::HTML::EVENT_ATTRIBUTES.each do |event_attribute|
with "with naughty #{event_attribute} attribute" do
naughty_attributes = { event_attribute => "alert(1);" }
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