CVE-2011-2536 Information

Description

chan_sip.c in the SIP channel driver in Asterisk Open Source 1.4.x before 1.4.41.2 1.6.2.x before 1.6.2.18.2 and 1.8.x before 1.8.4.4 and Asterisk Business Edition C.3.x before C.3.7.3 disregards the alwaysauthreject option and generates different responses for invalid SIP requests depending on whether the user account exists which allows remote attackers to enumerate account names via a series of requests.

Reference

http://downloads.asterisk.org/pub/security/AST-2011-011.html http://downloads.asterisk.org/pub/security/AST-2011-011-1.8.diff http://www.securitytracker.com/id?1025734