Vulnerability identifier: #VU12321

Vulnerability risk: Low

CVSSv3.1: 2.7 [CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2008-3903

CWE-ID: CWE-200

Exploitation vector: Network

Exploit availability: No

Description
Asterisk Open Source 1.2.x before 1.2.32, 1.4.x before 1.4.24.1, and 1.6.0.x before 1.6.0.8; Asterisk Business Edition A.x.x, B.x.x before B.2.5.8, C.1.x.x before C.1.10.5, and C.2.x.x before C.2.3.3; s800i 1.3.x before 1.3.0.2; and Trixbox PBX 2.6.1, when Digest authentication and authalwaysreject are enabled, generates different responses depending on whether a SIP username is valid, which allows remote attackers to enumerate valid usernames.

Mitigation
Install update from vendor's website.

External links
http://downloads.asterisk.org/pub/security/AST-2009-003.html
http://misel.com/?p=52
http://security.gentoo.org/glsa/glsa-200905-01.xml
http://www.debian.org/security/2009/dsa-1952
http://www.securityfocus.com/bid/34353
http://www.vupen.com/english/advisories/2009/0933
http://exchange.xforce.ibmcloud.com/vulnerabilities/45059

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.