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Issue 793628 link

Starred by 2 users

Issue metadata

Status: Verified
Closed: Jan 2018
EstimatedDays: ----
NextAction: ----
OS: Linux , Android , Windows , iOS , Chrome , Mac , Fuchsia
Pri: 1
Type: Bug-Security

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Security: IDN URL Spoofing with Cyrillic

Reported by, Dec 10 2017

Issue description

Chrome Version: 65.0.3289.0 (Official Build) canary (64-bit)
Operating System: All

- Expected:

- Actual:
Components: UI>Browser>Omnibox UI>Internationalization
Labels: Security_Severity-Medium OS-Android OS-Chrome OS-Fuchsia OS-iOS OS-Linux OS-Mac OS-Windows Pri-1
Status: Untriaged (was: Unconfirmed)

Comment 2 by, Dec 11 2017

Components: UI>Security>UrlFormatting
ҏ: U+048F  :  no decomposition
ұ: U+04B1 (Kazakh) : no decomposition.  confusables list has  'y' (Latin Small Letter Y) + combining short stroke overlay (U+0335). 

Both are under 'Extended Cyrillic' subheading.  (\p{subhead=Extended%20Cyrillic} )

When dropping rarely used LGC recently, I didn't drop this and 'Cyrillic supplement' block (and 'Cyrillic - Historic*' sub-block) but meant to review them for further action. 

Project Member

Comment 3 by, Dec 11 2017

Status: Assigned (was: Untriaged)

Comment 4 by, Dec 11 2017

comment 2 was sent without being completed. 
At the moment, mapping U+048F (ҏ ) to 'p' and U+04B1 (ұ) to 'y' before calculating the skeleton (instead of disallowing them downright) is  the best solution. 

Moreover, 'Extended Cyrillic' sub-block and 'Cyrillic supplementary' block have to be examined for other cases like that. 

Comment 5 by, Dec 11 2017

> Moreover, 'Extended Cyrillic' sub-block and 'Cyrillic supplementary' block have to be examined for other cases like that.  :  NFD_Inert Cyrillic letters currently allowed. Need to go over them all to see if there's any letters to add to the list of characters to be mapped to ASCII-latin before calculating the skeleton. 

Comment 6 by, Dec 11 2017

> 'Cyrillic - Historic*' sub-block

Forgot that this sub-block is not allowed anyway. 

Comment 7 by, Dec 11 2017

> add to the list of characters to be mapped to ASCII-latin before calculating the skeleton. 

The list is used to match against top domains (virtually all of them in ASCII-Latin. There's only one exception). 

Comment 8 by, Dec 11 2017

A subset of characters to consider from

Labels: Security_Impact-Stable
Repros in M63.
Project Member

Comment 10 by, Dec 13 2017

Labels: M-63

Comment 11 by, Dec 16 2017

I thought of two ways to handle this, but it turned out that the 2nd way wouldn't work. So, I'm left with the following:

Map U+049B (қ) etc to 'k' (do the same for other Cyrillic characters with "accent" that are not decomposed into base + combining mark) before calculating the skeleton of an incoming domain. 

Project Member

Comment 12 by, Dec 30 2017

jshin: Uh oh! This issue still open and hasn't been updated in the last 14 days. This is a serious vulnerability, and we want to ensure that there's progress. Could you please leave an update with the current status and any potential blockers?

If you're not the right owner for this issue, could you please remove yourself as soon as possible or help us find the right one?

If the issue is fixed or you can't reproduce it, please close the bug. If you've started working on a fix, please set the status to Started.

Thanks for your time! To disable nags, add the Disable-Nags label.

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Comment 13 by, Jan 10 2018

I'm also looking at these two sets:

[:IdentifierStatus=Allowed:] &  [:Ll:] & [[:sc=Latin:]] & [:NFD_Inert=Yes:]

[:IdentifierStatus=Allowed:] &  [:Ll:] & [[:sc=Greek:]] & [:NFD_Inert=Yes:]

Comment 14 by, Jan 10 2018

For Latin, use this set: 

[:IdentifierStatus=Allowed:] &  [:Ll:] & [[:sc=Latin:] -[\u01cd-\u01dc] - [\u1e00-\u1e9b] - [\ua720-\ua7ff]] & [:NFD_Inert=Yes:]

Comment 16 by, Jan 10 2018

Status: Started (was: Assigned)
Project Member

Comment 17 by, Jan 13 2018

The following revision refers to this bug:

commit fe3c71592ccc6fd6f3909215e326ffc8fe0c35ce
Author: Jungshik Shin <>
Date: Sat Jan 13 01:11:09 2018

Add more confusable character map entries

When comparing domain names with top 10k domain names for confusability,
characters with diacritics are decomposed into base + diacritic marks
(Unicode Normalization Form D) and diacritics are dropped before
calculating the confusability skeleton because two characters with and
without a diacritics is NOT regarded as confusable.

However, there are a dozen of characters (most of them are Cyrillic)
with a diacritic-like mark attached but they are not decomposed into
base + diacritics by NFD (e.g. U+049B, қ; Cyrillic Small Letter Ka
with Descender).  This CL treats them the same way as their "base"
characters. For instance, қ (U+049B) is treated as confusable with
Latin k because к (U+043A; Cyrillic Small Letter Ka) is.

They're curated from the following sets:

[:IdentifierStatus=Allowed:] &  [:Ll:] &
  [[:sc=Cyrillic:] -
  [\ua640-\ua69f][\ua720-\ua7ff]]] &

[:IdentifierStatus=Allowed:] &  [:Ll:] &
  [[:sc=Latin:] - [[\u01cd-\u01dc][\u1e00-\u1e9b][\ua720-\ua7ff]]] &

[:IdentifierStatus=Allowed:] &  [:Ll:] & [[:sc=Greek:]] &

Bug:  793628 , 798892 
Test: components_unittests --gtest_filter=*IDN*
Change-Id: I20c6af13defa295f6952f33d75987e87ce1853d0
Commit-Queue: Jungshik Shin <>
Reviewed-by: Eric Lawrence <>
Reviewed-by: Peter Kasting <>
Cr-Commit-Position: refs/heads/master@{#529129}

Thanks for the fix :-)

Comment 19 by, Jan 13 2018

Status: Fixed (was: Started)
Thank you for the report :-). 

Project Member

Comment 20 by, Jan 13 2018

Labels: -Restrict-View-SecurityTeam Restrict-View-SecurityNotify
Labels: reward-topanel

Comment 22 by, Jan 16 2018

Labels: -M-63 M-64
Too late for 63. Will try to get in for 64 after baking in canary/dev. 

Comment 23 by, Jan 16 2018

Status: Verified (was: Fixed)
Verified in two versions of canary (the latest being 65.0.3322.3 ). 

Comment 24 by, Jan 17 2018

Labels: Merge-Request-64
Made the latest dev channel release as well. 

Asking for merge approval to 64. The actual change [1]  is rather small (a lot of test entries were added along with comments). 


Project Member

Comment 25 by, Jan 17 2018

Labels: -Merge-Request-64 Hotlist-Merge-Review Merge-Review-64
This bug requires manual review: Less than 2 days to go before AppStore submit on M64
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), kbleicher@(ChromeOS), abdulsyed@(Desktop)

For more details visit - Your friendly Sheriffbot
I don't think this is critical enough to be cherry picked into M64 at this point but letting awhalley@ to make the call.
Labels: -M-64 M-65
cmasso@, yep, this can wait until M65
Labels: -Hotlist-Merge-Review -Merge-Review-64 Merge-Rejected-64
Labels: -reward-topanel reward-unpaid reward-500
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Thanks for the report, the VRP panel awarded $500 for this.
Labels: -reward-unpaid reward-inprocess
Labels: Release-0-M65
Labels: CVE-2018-6078
Project Member

Comment 34 by, Apr 21 2018

Labels: -Restrict-View-SecurityNotify allpublic
This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit - Your friendly Sheriffbot
Labels: CVE_description-missing
Labels: idn-spoof
Labels: -CVE_description-missing CVE_description-submitted

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