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Computer vulnerabilities of Avahi

computer vulnerability announce CVE-2017-6519

Avahi: information disclosure and DDos via mDNS on IPv6

Synthesis of the vulnerability

An attacker can query the mDNS service of Avahi, in order to obtain sensitive information about the network, or to amplify a denial of service attack.
Impacted products: Avahi, openSUSE Leap, SUSE Linux Enterprise Desktop, SLES, Ubuntu.
Severity: 2/4.
Consequences: data reading, denial of service on service.
Provenance: internet client.
Number of vulnerabilities in this bulletin: 2.
Creation date: 02/05/2017.
Identifiers: CVE-2017-6519, CVE-2018-1000845-REJECT, openSUSE-SU-2019:0128-1, openSUSE-SU-2019:0197-1, RHBUG-1426712, SUSE-SU-2019:0179-1, SUSE-SU-2019:0285-1, SUSE-SU-2019:13947-1, USN-3876-1, USN-3876-2, VIGILANCE-VUL-22617.

Description of the vulnerability

The mDNS (Multicast DNS) protocol allows local computers to discover services available on their networks.

However, the IPv6 mDNS implementation in Avahi accepts to reply to Unicast queries coming from outside its network.

This vulnerability is a variant of VIGILANCE-VUL-16510.

An attacker can therefore query the mDNS service of Avahi, in order to obtain sensitive information about the network, or to amplify a denial of service attack.
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vulnerability CVE-2015-2809

mDNS: information disclosure and DDos

Synthesis of the vulnerability

An attacker can query the mDNS service, in order to obtain sensitive information about the network, or to amplify a denial of service attack.
Impacted products: Avahi, DNS protocol, Synology DSM.
Severity: 2/4.
Consequences: data reading, denial of service on service.
Provenance: internet client.
Creation date: 01/04/2015.
Identifiers: CVE-2015-2809, VIGILANCE-VUL-16510, VU#550620.

Description of the vulnerability

The mDNS (Multicast DNS) protocol allows local computers to discover services available on their networks.

However, some mDNS implementations accept to reply to Unicast queries coming from outside their network.

An attacker can therefore query the mDNS service, in order to obtain sensitive information about the network, or to amplify a denial of service attack.
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vulnerability announce CVE-2010-2244

Avahi: denial of service via DNS

Synthesis of the vulnerability

An attacker can send a malformed DNS packet, in order to stop the Avahi daemon.
Impacted products: Avahi, Debian, Fedora, Mandriva Linux, OpenSolaris, RHEL.
Severity: 2/4.
Consequences: denial of service on service.
Provenance: intranet client.
Creation date: 07/07/2010.
Identifiers: CERTA-2002-AVI-279, CVE-2010-2244, DSA-2086-1, FEDORA-2010-10581, FEDORA-2010-10584, MDVSA-2010:204, RHSA-2010:0528-01, VIGILANCE-VUL-9742.

Description of the vulnerability

The Avahi daemon automatically process the network configuration of the system.

The avahi_recv_dns_packet_ipv4/6() functions of the file avahi-core/socket.c decode received UDP+DNS/mDNS (Multicast DNS) packets.

When an attacker sends a packet with an invalid UDP checksum, followed by a valid packet, the avahi_recv_dns_packet_ipv4/6() functions use a null packet size, which generate an assertion error.

An attacker can therefore send a malformed DNS packet, in order to stop the Avahi daemon.
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computer vulnerability alert CVE-2007-3372

Avahi: denial of service via D-Bus

Synthesis of the vulnerability

A local attacker can stop the Avahi daemon by using a special D-Bus message.
Impacted products: Avahi, Debian, Mandriva Linux, openSUSE, SLES.
Severity: 1/4.
Consequences: denial of service on service.
Provenance: user account.
Creation date: 18/09/2007.
Identifiers: BID-24614, CVE-2007-3372, DSA-1690-1, MDKSA-2007:185, SUSE-SR:2007:014, VIGILANCE-VUL-7176.

Description of the vulnerability

The Avahi system permits to discover services offered by a local network.

The D-Bus environment permits applications to exchange information. It is based on a daemon and a library which is used by software. Avahi uses D-Bus.

An attacker can use a D-Bus message with an empty TXT field in order to generate an assertion error in Avahi. This error stops the daemon.

A local attacker can therefore create a denial of service.
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computer vulnerability CVE-2006-6870

Avahi: denial of service via DNS

Synthesis of the vulnerability

A network attacker can construct a malicious DNS packet generating an infinite loop in Avahi.
Impacted products: Avahi, Fedora, Mandriva Linux, openSUSE, SLES.
Severity: 1/4.
Consequences: denial of service on service.
Provenance: intranet server.
Creation date: 08/01/2007.
Identifiers: BID-21881, CVE-2006-6870, FEDORA-2007-018, FEDORA-2007-019, MDKSA-2007:003, SUSE-SR:2007:007, VIGILANCE-VUL-6435.

Description of the vulnerability

The Avahi system permits to discover services offered by a local network.

The DNS protocol defines a compression method to suppress redundant segments. For example, a message can contain;
  www.domain.dom
  dns.domain.dom
In this case, the second occurrence of "domain.dom" can be replaced by the offset of the first one.

However, the consume_labels() function of avahi-core/dns.c does not correctly check offsets. They can point to current offset in order to generate an infinite loop.

A remote attacker can thus send a malicious DNS compressed packet in order to generate a denial of service on Avahi.

This vulnerability is a particular case of the VIGILANCE-VUL-4978 generic bulletin.
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computer vulnerability note CVE-2006-5461

Avahi: information edition via netlink

Synthesis of the vulnerability

A local attacker can send malicious netlink messages to Avahi in order to alter returned information.
Impacted products: Avahi, Fedora, Mandriva Linux.
Severity: 1/4.
Consequences: data creation/edition.
Provenance: user shell.
Creation date: 21/11/2006.
Identifiers: CVE-2006-5461, FEDORA-2006-1339, FEDORA-2006-1340, MDKSA-2006:215, VIGILANCE-VUL-6329.

Description of the vulnerability

The Avahi system permits to discover services offered by a local network.

The netlink mechanism is used to exchange data between kernel and user space.

When Avahi receives a netlink message, it does not check if it originates from the kernel.

A local attacker can thus send netlink messages to Avahi in order for example to invite user to connect to a malicious computer.
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