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computer vulnerability bulletin CVE-2013-2053

Openswan: buffer overflow of atodn

Synthesis of the vulnerability

When Opportunistic Encryption is enabled ("oe=yes"), an attacker can generate a buffer overflow in Openswan, in order to trigger a denial of service, and possibly to execute code.
Vulnerable products: Debian, Openswan, RHEL, SLES.
Severity of this weakness: 2/4.
Consequences of an attack: user access/rights.
Hacker's origin: intranet client.
Creation date: 15/05/2013.
Références of this bulletin: BID-59838, CVE-2013-2053, DSA-2893-1, MDVSA-2013:231, RHSA-2013:0827-01, SUSE-SU-2013:1150-1, VIGILANCE-VUL-12828.

Description of the vulnerability

When Opportunistic Encryption is enabled ("oe=yes"), the IKE pluto daemon queries DNS TXT records, in order to obtain public keys.

These records contain the name of the IPsec gateway. This name is transmitted to the atoid() function, then to atodn(). However, the atodn() function stores the name in a array of three bytes. An overflow thus occurs.

In order to exploit this vulnerability, the attacker has to ask to connect to an IP address for which he can spoof a reverse DNS TXT reply.

An attacker can therefore generate a buffer overflow in Openswan, in order to trigger a denial of service, and possibly to execute code.

This vulnerability has the same origin as VIGILANCE-VUL-12827 and VIGILANCE-VUL-12829.
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