Vulnerability identifier: #VU6619

Vulnerability risk: Medium

CVSSv3.1: 7.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-119

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Asterisk Open Source
Server applications / Conferencing, Collaboration and VoIP solutions
Certified Asterisk
Server applications / Conferencing, Collaboration and VoIP solutions

Vendor: Digium (Linux Support Services)

Description
The vulnerability allows a remote attacker to cause DoS condition on the target system.

The weakness exists due to insufficient allocation of a buffer size by the PJSIP RFC 2543 transaction key generation algorithm. A remote attacker can send a specially crafted Session Initiation Protocol (SIP) packet containing a long CSeq header value along with a Via header with no branch parameter, trigger memory corruption and cause the affected device to crash.

Successful exploitation of the vulnerability results in denial of service.

Mitigation
Update Asterisk to version 13.15.1 and 14.4.1.
Update Certified Asterisk to version 13.13-cert.

Vulnerable software versions

Asterisk Open Source: 13.0.1 - 13.15.0, 14.0 - 14.4.0

Certified Asterisk: 13.13

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External links
http://downloads.asterisk.org/pub/security/AST-2017-002.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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