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Debian Security Advisory DSA 3097-1 (unbound - security update)
Information
Severity
Severity
Family
Family
CVSSv2 Base
CVSSv2 Base
CVSSv2 Vector
CVSSv2 Vector
Solution Type
Solution Type
Created
Created
Modified
Modified
Summary
Florian Maury from ANSSI discovered that unbound, a validating, recursive, and caching DNS resolver, was prone to a denial of service vulnerability. An attacker crafting a malicious zone and able to emit (or make emit) queries to the server can trick the resolver into following an endless series of delegations, leading to resource exhaustion and huge network usage.
Insight
Insight
Unbound is a recursive-only caching DNS server which can perform DNSSEC validation of results. It implements only a minimal amount of authoritative service to prevent leakage to the root nameservers: forward lookups for localhost, reverse for 127.0.0.1 and ::1, and NXDOMAIN for zones served by AS112. Stub and forward zones are supported.
Affected Software
Affected Software
unbound on Debian Linux
Detection Method
Detection Method
This check tests the installed software version using the apt package manager.
Solution
Solution
For the stable distribution (wheezy), this problem has been fixed in version 1.4.17-3+deb7u2. For the upcoming stable distribution (jessie), this problem has been fixed in version 1.4.22-3. For the unstable distribution (sid), this problem has been fixed in version 1.4.22-3. We recommend that you upgrade your unbound packages.