Rule Category

PROTOCOL-VOIP -- Snort has detected traffic that may indicate the presence of the VOIP protocol or vulnerabilities in the VOIP protocol on the network.

Alert Message

PROTOCOL-VOIP Digium Asterisk multiple malformed Accept headers denial of service attempt

Rule Explanation

This event is generated when an attempt to exploit CVE-2018-7284 is detected. Impact: Attempted Denial of Service Details: When processing a SUBSCRIBE request the res_pjsip_pubsub module stores the accepted formats present in the Accept headers of the request. This code did not limit the number of headers it processed despite having a fixed limit of 32. If more than 32 Accept headers were present the code would write outside of its memory and cause a crash. Ease of Attack: Simple, a public proof of concept exploit exists.

What To Look For

Known Usage

No public information

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

MITRE ATT&CK Framework

Tactic:

Technique:

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

CVE

Additional Links

CVE Additional Information

CVE-2018-7284
A Buffer Overflow issue was discovered in Asterisk through 13.19.1, 14.x through 14.7.5, and 15.x through 15.2.1, and Certified Asterisk through 13.18-cert2. When processing a SUBSCRIBE request, the res_pjsip_pubsub module stores the accepted formats present in the Accept headers of the request. This code did not limit the number of headers it processed, despite having a fixed limit of 32. If more than 32 Accept headers were present, the code would write outside of its memory and cause a crash.
Details
Severity Base Score7.5
Impact Score3.6 Exploit Score3.9
Confidentiality ImpactNONE Integrity ImpactNONE
Availability ImpactHIGH Attack VectorNETWORK
ScopeUNCHANGED User InteractionNONE
Authentication Ease of AccessLOW
Privileges RequiredNONE