Asterisk TLS Certificate Common Name NULL Byte Vulnerability (AST-2015-003)

medium Nessus Plugin ID 82901
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VPR Score: 3.7


A telephony application running on the remote host is affected by a certificate validation vulnerability.


According to its SIP banner, the version of Asterisk running on the remote host is potentially affected by flaw related to certificate validation when registering a SIP TLS device due to not properly verifying a server hostname against an X.509 Common Name (CN) field that has a NULL byte appended after the expected results. A man-in-the-middle attacker can exploit this, via a crafted certificate, to spoof arbitrary SSL servers and intercept network traffic.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.


Upgrade to Asterisk / 11.17.1 / 12.8.2 / 13.3.2 / 1.8.28-cert5 / 11.6-cert11 / 13.1-cert2, or apply the appropriate patch listed in the Asterisk advisory.

See Also

Plugin Details

Severity: Medium

ID: 82901

File Name: asterisk_ast_2015_003.nasl

Version: 1.9

Type: remote

Family: Misc.

Published: 4/20/2015

Updated: 6/27/2018

Dependencies: asterisk_detection.nasl

Configuration: Enable paranoid mode

Risk Information

Risk Factor: Medium

VPR Score: 3.7

CVSS v2.0

Base Score: 4.3

Temporal Score: 3.2

Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N

Temporal Vector: E:U/RL:OF/RC:C

Vulnerability Information

CPE: cpe:/a:digium:asterisk

Required KB Items: asterisk/sip_detected, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 4/8/2015

Vulnerability Publication Date: 4/8/2015

Reference Information

CVE: CVE-2015-3008

BID: 74022