Digium Asterisk up to 14.2 SDP Offer res_format_attr_opus.c sdp_fmtp_get memory corruption

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3$0-$5k0.00

A vulnerability, which was classified as problematic, has been found in Digium Asterisk up to 14.2 (Communications System). This issue affects the function sdp_fmtp_get of the file res_format_attr_opus.c of the component SDP Offer Handler. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is availability.

The weakness was shared 12/08/2016 by jorgen as AST-2016-008: Crash on SDP offer or answer from endpoint using Opus as confirmed mailinglist post (Full-Disclosure). The advisory is shared at seclists.org. The vendor cooperated in the coordination of the public release. The identification of this vulnerability is CVE-2016-9937. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The advisory points out:

If an SDP offer or answer is received with the Opus codec and with the format parameters separated using a space the code responsible for parsing will recursively call itself until it crashes. This occurs as the code does not properly handle spaces separating the parameters.

The vulnerability scanner Nessus provides a plugin with the ID 95926 (Asterisk Opus Codec DoS (AST-2016-008)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Misc.. The advisory illustrates:

This does NOT require the endpoint to have Opus configured in Asterisk. This also does not require the endpoint to be authenticated. If guest is enabled for chan_sip or anonymous in chan_pjsip an SDP offer or answer is still processed and the crash occurs.

Applying the patch 13.13.1/14.2.1 is able to eliminate this problem. The bugfix is ready for download at downloads.asterisk.org. A possible mitigation has been published immediately after the disclosure of the vulnerability. The mailinglist post contains the following remark:

The code has been updated to properly handle spaces separating parameters in the fmtp line. Upgrade to a released version with the fix incorporated or apply patch.

The vulnerability is also documented in the databases at Tenable (95926) and SecurityFocus (BID 94792†). The entry VDB-93990 is related to this item. If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
unlockunlockunlockunlockunlockunlock
unlockunlockunlockunlockunlockunlock
unlockunlockunlockunlockunlockunlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Dayunlockunlockunlockunlock
Todayunlockunlockunlockunlock

Nessus ID: 95926
Nessus Name: Asterisk Opus Codec DoS (AST-2016-008)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍

OpenVAS ID: 103497
OpenVAS Name: Asterisk SDP Offer DoS Vulnerability
OpenVAS File: 🔍
OpenVAS Family: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Patch: 13.13.1/14.2.1

Timelineinfo

12/08/2016 🔍
12/08/2016 +0 days 🔍
12/09/2016 +1 days 🔍
12/12/2016 +2 days 🔍
12/12/2016 +0 days 🔍
10/05/2022 +2123 days 🔍

Sourcesinfo

Vendor: digium.com

Advisory: AST-2016-008: Crash on SDP offer or answer from endpoint using Opus
Researcher: jorgen
Status: Confirmed
Coordinated: 🔍

CVE: CVE-2016-9937 (🔍)
GCVE (CVE): GCVE-0-2016-9937
GCVE (VulDB): GCVE-100-93989
SecurityFocus: 94792
SecurityTracker: 1037407

See also: 🔍

Entryinfo

Created: 12/09/2016 09:00 AM
Updated: 10/05/2022 09:01 AM
Changes: 12/09/2016 09:00 AM (52), 12/24/2017 09:38 AM (17), 10/05/2022 08:55 AM (5), 10/05/2022 08:57 AM (11), 10/05/2022 09:01 AM (1)
Complete: 🔍
Cache ID: 18:257:40

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Might our Artificial Intelligence support you?

Check our Alexa App!