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Link label security #1515

Merged
merged 3 commits into from Jul 4, 2019
Merged

Link label security #1515

merged 3 commits into from Jul 4, 2019

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UziTech
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@UziTech UziTech commented Jul 2, 2019

Marked version: master

Description

Fixes the ReDOS vulnerability in #1493

This does break a current test with a single backtick in a link label

[the ` character](/url)

That markdown can be fixed by escaping the backtick

[the \` character](/url)

Fixes #1493

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  • Test(s) exist to ensure functionality and minimize regression

Committer

In most cases, this should be a different person than the contributor.

  • Draft GitHub release notes have been updated.
  • CI is green (no forced merge required).
  • Merge PR

@UziTech UziTech added category: links L0 - security A security vulnerability within the Marked library is discovered labels Jul 2, 2019
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UziTech commented Jul 2, 2019

If this PR is merged I will create a new issue about the single backtick so we can still track it.

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UziTech commented Jul 2, 2019

This is a temporary fix. Links will need to be parsed with a function to be fully spec compliant to allow the single backtick along with nested brackets like we are parsing the href.

@@ -1,3 +1,3 @@
[the `]` character](/url)

[the ` character](/url)
[the \` character](/url)
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So this PR is going to introduce a regression but fix a redos issue?

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yes

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LGTM

@UziTech UziTech merged commit 0ee3aa9 into markedjs:master Jul 4, 2019
@UziTech UziTech mentioned this pull request Jul 5, 2019
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SISheogorath added a commit to hedgedoc/hedgedoc that referenced this pull request Aug 15, 2019
Meta-marked 0.4.4 which we used from our git repository contains a
RegexDOS attack in the marked dependency. The dependency was already
updated in our meta-marked repository, but not updated in yarn.

This made us still vulnerable to this ReDOS which was able to cause a
DOS attack on the server when updating a note.

For Details:

https://github.com/markedjs/marked/releases/tag/v0.7.0
markedjs/marked#1515

What is a ReDOS?

A ReDOS attack is a DOS attack where an attacker targets a
not-well-written Regular Expression. Regular expressions try to build a
tree of all possibilities it can match in order to figure out if the
given statement is valid or not. A ReDOS attack abuses this concept by
providing a statement that doesn't match but causes extremly huge trees
that simply lead to exhausting CPU usage.

For more details see: https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS

Credit:

Huge thanks to @bitinerant for finding this and handling it with a
responsible disclosure.

Also thanks to the `marked`-team for fixing things already.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>
SISheogorath added a commit to SISheogorath/codimd-server that referenced this pull request Sep 5, 2019
Meta-marked 0.4.4 which we used from our git repository contains a
RegexDOS attack in the marked dependency. The dependency was already
updated in our meta-marked repository, but not updated in yarn.

This made us still vulnerable to this ReDOS which was able to cause a
DOS attack on the server when updating a note.

For Details:

https://github.com/markedjs/marked/releases/tag/v0.7.0
markedjs/marked#1515

What is a ReDOS?

A ReDOS attack is a DOS attack where an attacker targets a
not-well-written Regular Expression. Regular expressions try to build a
tree of all possibilities it can match in order to figure out if the
given statement is valid or not. A ReDOS attack abuses this concept by
providing a statement that doesn't match but causes extremly huge trees
that simply lead to exhausting CPU usage.

For more details see: https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS

Credit:

Huge thanks to @bitinerant for finding this and handling it with a
responsible disclosure.

Also thanks to the `marked`-team for fixing things already.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>
@UziTech UziTech deleted the link-label-security branch September 11, 2019 21:21
zhenalexfan pushed a commit to zhenalexfan/MarkdownHan that referenced this pull request Nov 8, 2021
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Extremely slow processing on malformed markdown (0.6.2)
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