Bug 732658 (CVE-2011-3188)

Summary: CVE-2011-3188 kernel: net: improve sequence number generation
Product: [Other] Security Response Reporter: Eugene Teo (Security Response) <eteo>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anton, arozansk, bhu, davej, dhoward, fhrbata, haliu, jkacur, kernel-mgr, kmcmartin, lgoncalv, lwang, plougher, pmatouse, rt-maint, sforsber, tcallawa, vgoyal, williams, zzhou
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2012-05-10 08:21:46 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 732662, 732663, 732664, 732665, 732666, 743808, 748682, 761362    
Bug Blocks: 731920    

Description Eugene Teo (Security Response) 2011-08-23 08:40:21 UTC
Dan Kaminsky pointed out that using partial MD4 and using that to generate a sequence number, of which only 24-bits are truly unguessable, seriously undermine the goals of random sequence number generation.

In particular, with only 24-bits being truly unguessable, packet injection into a session using even something like brute force is a real potential possibility.

We only use 24-bits because we regenerate the random number every 5 minutes "just in case."  But what does is trade a "we don't know" kind of theoretical issue for a provably real one (brute force attack).

Therefore [Dave Miller] moving us more in line with RFC1948 (as well as OpenBSD and Solaris), to use MD5 and a full 32-bit result in the generated sequence number.

MD5 was selected as a compromise between performance loss and theoretical ability to be compromised.  Willy Tarreau did extensive testing and SHA1 was found to harm performance too much to be considered seriously at this time.

We may later add a sysctl for various modes (ie. a "super secure" mode that uses SHA1 if people want that, and an "insecure" mode that doesn't use cryptographic hashing at all for people in protected environments where that might be safe to do).

[Dave Miller] also moved the sequence number generators out of random.c (they never really belonged there, and are only there due to historical artifacts), and fixed a bug in DCCP sequence number generation (on ipv6 the 43-bit sequence number was truncated to 32-bits).


Red Hat would like to thank Dan Kaminsky for reporting this issue.

Comment 3 Eugene Teo (Security Response) 2011-08-23 09:01:11 UTC

Upstream commits:
crypto: Move md5_transform to lib/md5.c
net: Compute protocol sequence numbers and fragment IDs using MD5

Comment 4 Petr Matousek 2011-08-26 10:06:50 UTC

This issue affects the Linux kernel as shipped with Red Hat Enterprise Linux 4, 5, 6, and Red Hat Enterprise MRG. It has been addressed in Red Hat Enterprise Linux 5, 6, and Red Hat Enterprise MRG via https://rhn.redhat.com/errata/RHSA-2011-1386.html, https://rhn.redhat.com/errata/RHSA-2011-1465.html, and https://rhn.redhat.com/errata/RHSA-2012-0010.html. Red Hat Enterprise Linux 4 is now in Production 3 of the maintenance life-cycle, https://access.redhat.com/support/policy/updates/errata/, therefore the fix for this issue is not currently planned to be included in the future updates.

Comment 11 errata-xmlrpc 2011-10-20 17:29:10 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2011:1386 https://rhn.redhat.com/errata/RHSA-2011-1386.html

Comment 12 Eugene Teo (Security Response) 2011-10-25 03:54:08 UTC
Created kernel tracking bugs for this issue

Affects: fedora-all [bug 748682]

Comment 13 errata-xmlrpc 2011-10-26 15:32:50 UTC
This issue has been addressed in following products:

  RHEV-H, V2V and Agents for RHEL-5

Via RHSA-2011:1408 https://rhn.redhat.com/errata/RHSA-2011-1408.html

Comment 14 errata-xmlrpc 2011-11-01 17:14:01 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5.6.Z - Server Only

Via RHSA-2011:1419 https://rhn.redhat.com/errata/RHSA-2011-1419.html

Comment 15 errata-xmlrpc 2011-11-22 16:50:12 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2011:1465 https://rhn.redhat.com/errata/RHSA-2011-1465.html

Comment 17 errata-xmlrpc 2012-01-10 20:16:10 UTC
This issue has been addressed in following products:

  MRG for RHEL-6 v.2

Via RHSA-2012:0010 https://rhn.redhat.com/errata/RHSA-2012-0010.html