CVE-2017-5495

All versions of Quagga, 0.93 through 1.1.0, are vulnerable to an unbounded memory allocation in the telnet 'vty' CLI, leading to a Denial-of-Service of Quagga daemons, or even the entire host. When Quagga daemons are configured with their telnet CLI enabled, anyone who can connect to the TCP ports can trigger this vulnerability, prior to authentication. Most distributions restrict the Quagga telnet interface to local access only by default. The Quagga telnet interface 'vty' input buffer grows automatically, without bound, so long as a newline is not entered. This allows an attacker to cause the Quagga daemon to allocate unbounded memory by sending very long strings without a newline. Eventually the daemon is terminated by the system, or the system itself runs out of memory. This is fixed in Quagga 1.1.1 and Free Range Routing (FRR) Protocol Suite 2017-01-10.

All versions of Quagga, 0.93 through 1.1.0, are vulnerable to an unbounded memory allocation in the telnet 'vty' CLI, leading to a Denial-of-Service of Quagga daemons, or even the entire host (CVE-2017-5495).

These are all security issues fixed in the libfpm_pb0-1.2.4-2.14 package on the GA media of openSUSE Tumbleweed.

This update provides Quagga 1.1.1, which brings several fixes and enhancements.

Security issues fixed:

• CVE-2017-5495: Telnet 'vty' interface DoS due to unbounded memory allocation. (bsc#1021669)
• CVE-2016-1245: Stack overrun in IPv6 RA receive code. (bsc#1005258)

Bug fixes:

• Do not enable zebra's TCP interface (port 2600) to use default UNIX socket for communication between the daemons. (fate#323170)

Between 0.99.22.1 and 1.1.1 the following improvements have been implemented:

• Changed the default of 'link-detect' state, controlling whether zebra will respond to link-state events and consider an interface to be down when link is down. To retain the current behavior save your config before updating, otherwise remove the 'link-detect' flag from your config prior to updating. There is also a new global 'default link-detect (on|off)' flag to configure the global default.
• Greatly improved nexthop resolution for recursive routes.
• Event driven nexthop resolution for BGP.
• Route tags support.
• Transport of TE related metrics over OSPF, IS-IS.
• IPv6 Multipath for zebra and BGP.
• Multicast RIB support has been extended. It still is IPv4 only.
• RIP for IPv4 now supports equal-cost multipath (ECMP).
• route-maps have a new action 'set ipv6 next-hop peer-address'.
• route-maps have a new action 'set as-path prepend last-as'.
• 'next-hop-self all' to override nexthop on iBGP route reflector setups.
• New pimd daemon provides IPv4 PIM-SSM multicast routing.
• IPv6 address management has been improved regarding tentative addresses. This is visible in that a freshly configured address will not immediately be marked as usable.
• Recursive route support has been overhauled. Scripts parsing 'show ip route' output may need adaptation.
• A large amount of changes has been merged for ospf6d. Careful evaluation prior to deployment is recommended.
• Multiprotocol peerings over IPv6 now try to find a more appropriate IPv4 nexthop by looking at the interface.
• Relaxed bestpath criteria for multipath and improved display of multipath routes in 'show ip bgp'. Scripts parsing this output may need to be updated.
• Support for iBGP TTL security.

This update for quagga fixes the following security issues:

• The Quagga BGP daemon contained a bug in the AS_PATH size calculation that could have been exploited to facilitate a remote denial-of-service attack via specially crafted BGP UPDATE messages. [CVE-2017-16227, bsc#1065641]

• The Quagga BGP daemon did not check whether data sent to peers via NOTIFY had an invalid attribute length. It was possible to exploit this issue and cause the bgpd process to leak sensitive information over the network to a configured peer. [CVE-2018-5378, bsc#1079798]

• The Quagga BGP daemon used to double-free memory when processing certain forms of UPDATE messages. This issue could be exploited by sending an optional/transitive UPDATE attribute that all conforming eBGP speakers should pass along. Consequently, a single UPDATE message could have affected many bgpd processes across a wide area of a network. Through this vulnerability, attackers could potentially have taken over control of affected bgpd processes remotely. [CVE-2018-5379, bsc#1079799]

• It was possible to overrun internal BGP code-to-string conversion tables in the Quagga BGP daemon. Configured peers could have exploited this issue and cause bgpd to emit debug and warning messages into the logs that would contained arbitrary bytes. [CVE-2018-5380, bsc#1079800]

• The Quagga BGP daemon could have entered an infinite loop if sent an invalid OPEN message by a configured peer. If this issue was exploited, then bgpd would cease to respond to any other events. BGP sessions would have been dropped and not be reestablished. The CLI interface would have been unresponsive. The bgpd daemon would have stayed in this state until restarted. [CVE-2018-5381, bsc#1079801]

• The Quagga daemon's telnet 'vty' CLI contains an unbounded memory allocation bug that could be exploited for a denial-of-service attack on the daemon. This issue has been fixed. [CVE-2017-5495, bsc#1021669]

• The telnet 'vty' CLI of the Quagga daemon is no longer enabled by default, because the passwords in the default 'zebra.conf' config file are now disabled. The vty interface is available via 'vtysh' utility using pam authentication to permit management access for root without password. [bsc#1021669]

This update for quagga fixes the following issues:

• The Quagga BGP daemon contained a bug in the AS_PATH size calculation that could have been exploited to facilitate a remote denial-of-service attack via specially crafted BGP UPDATE messages. [CVE-2017-16227, bsc#1065641]

• The Quagga BGP daemon did not check whether data sent to peers via NOTIFY had an invalid attribute length. It was possible to exploit this issue and cause the bgpd process to leak sensitive information over the network to a configured peer. [CVE-2018-5378, bsc#1079798]

• The Quagga BGP daemon used to double-free memory when processing certain forms of UPDATE messages. This issue could be exploited by sending an optional/transitive UPDATE attribute that all conforming eBGP speakers should pass along. Consequently, a single UPDATE message could have affected many bgpd processes across a wide area of a network. Through this vulnerability, attackers could potentially have taken over control of affected bgpd processes remotely. [CVE-2018-5379, bsc#1079799]

• It was possible to overrun internal BGP code-to-string conversion tables in the Quagga BGP daemon. Configured peers could have exploited this issue and cause bgpd to emit debug and warning messages into the logs that would contained arbitrary bytes. [CVE-2018-5380, bsc#1079800]

• The Quagga BGP daemon could have entered an infinite loop if sent an invalid OPEN message by a configured peer. If this issue was exploited, then bgpd would cease to respond to any other events. BGP sessions would have been dropped and not be reestablished. The CLI interface would have been unresponsive. The bgpd daemon would have stayed in this state until restarted. [CVE-2018-5381, bsc#1079801]

• The Quagga daemon's telnet 'vty' CLI contains an unbounded memory allocation bug that could be exploited for a denial-of-service attack on the daemon. This issue has been fixed. [CVE-2017-5495, bsc#1021669]

• The telnet 'vty' CLI of the Quagga daemon is no longer enabled by default, because the passwords in the default 'zebra.conf' config file are now disabled. The vty interface is available via 'vtysh' utility using pam authentication to permit management access for root without password. [bsc#1021669]

Andreas Jaggi discovered that Quagga incorrectly handled certain BGP UPDATE messages. A remote attacker could possibly use this issue to cause Quagga to crash, resulting in a denial of service. (CVE-2017-16227)

Quentin Young discovered that Quagga incorrectly handled memory in the telnet vty CLI. An attacker able to connect to the telnet interface could possibly use this issue to cause Quagga to consume memory, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-5495)