Alerts This Week
Warning Icon 1 666
Alerts This Week
Warning Icon 1 666

Gentoo: 201606-12 Normal: libssh and libssh2 Denial of Service Attack

gentoo
Calendar Grey June 26, 2016
Dist Gentoo Esm H88
Numerous security flaws in libssh and libssh2 facilitate unauthorized access and potential Denial of Service attacks. Update immediately!
Multiple vulnerabilities have been found in libssh and libssh2, the worst of which allows remote attackers to cause Denial of Service.

Summary

libssh and libssh2 both have a bits/bytes confusion bug and generate an abnormaly short ephemeral secret for the diffie-hellman-group1 and diffie-hellman-group14 key exchange methods. The resulting secret is 128 bits long, instead of the recommended sizes of 1024 and 2048 bits respectively. Additionally, a double free on dangling pointers in initial key exchange packets within libssh could leave dangling pointers in the session crypto structures. It is possible to send a malicious kexinit package to eventually cause a server to do a double-free before this fix. This could be used for a Denial of Service attack.

Topics%20covered

Topics Covered

security advisory denial of service gentoo update instructions libssh libssh2

Resolution

All libssh users should upgrade to the latest version: # emerge --sync # emerge --ask --oneshot --verbose ">=net-libs/libssh-0.7.3"
All libssh2 users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=net-libs/libssh2-1.7.0"

References

[ 1 ] CVE-2014-8132 http://nvd.nist.gov/nvd.cfm?cvename=CVE-2014-8132 [ 2 ] CVE-2016-0739 http://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-0739 [ 3 ] CVE-2016-0787 http://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-0787

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: https://security.gentoo.org/glsa/201606-12
style>.gentoo_availability{display:block;}

Concerns

Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users' machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.

Severity: Normal
Title: libssh and libssh2: Multiple vulnerabilities
Date: June 26, 2016
Bugs: #533366, #575474, #575484
ID: 201606-12

Topics%20covered

Topics Covered

security advisory denial of service gentoo update instructions libssh libssh2

Synopsis

Multiple vulnerabilities have been found in libssh and libssh2, the worst of which allows remote attackers to cause Denial of Service.

Background

libssh is a mulitplatform C library implementing the SSHv2 and SSHv1 protocol on client and server side.

Get the latest News and Insights

Get the latest Linux and open source security news straight to your inbox.

Affected Packages

------------------------------------------------------------------- Package / Vulnerable / Unaffected ------------------------------------------------------------------- 1 net-libs/libssh < 0.7.3 >= 0.7.3 2 net-libs/libssh2 < 1.7.0 >= 1.7.0 ------------------------------------------------------------------- 2 affected packages

Impact

===== Remote attackers may gain access to confidential information due to the short keysize generated by libssh and libssh2, or cause a Denial of Service condition.

Workaround

There is no known workaround at this time.

Related News

Your message here