vulnerability alert CVE-2010-1224

Asterisk: bypassing ACLs

Synthesis of the vulnerability

An attacker, who is normally blocked by ACLs, can send SIP INVITE messages to Asterisk.

Severity: 2/4. Creation date: 26/02/2010.

Description of the vulnerability

The Asterisk program implements a VoIP service. A SIP INVITE message is used during the initialization of a VoIP session. The sip.conf configuration file of Asterisk can contain rules (ACLs with "permit" and "deny") to restrict clients which are allowed to send SIP INVITE messages. For example:   deny=64.198.7.0/24 (notation CIDR)   deny=64.198.7.0/255.255.255.0 (notation dotted-decimal) The acl.c file implements the CIDR notation using a 32 bit mask (mask<<(32-x)). However, if the indicated size is zero, the left shift of 32 bit is ignored. The resulting mask is thus invalid. An attacker, who is normally blocked by a "x.x.x.x/0" ACL, can therefore send SIP INVITE messages to Asterisk.

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Characteristics

Title: Asterisk: bypassing ACLs. Keywords: 198 255 32-x ACL ACLs Asterisk CIDR INVITE SIP VoIP bypassing. Identifiers: AST-2010-003, BID-38424, CVE-2010-1224, FEDORA-2010-3381, FEDORA-2010-3724, VIGILANCE-VUL-9476.

Information sources

Publications and announces

Solutions for this vulnerability

Patch or workaround

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