Vulnerability identifier: #VU55978

Vulnerability risk: Medium

CVSSv3.1: 6.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34749

CWE-ID: CWE-200

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
3000 Series Industrial Security Appliance (ISA)
Server applications / IDS/IPS systems, Firewalls and proxy servers
Cisco Web Security Appliance
Server applications / IDS/IPS systems, Firewalls and proxy servers
Snort
Server applications / IDS/IPS systems, Firewalls and proxy servers
Cisco Firepower Threat Defense (FTD)
Hardware solutions / Security hardware applicances

Vendor: Cisco Systems, Inc
Sourcefire

Description

The vulnerability allows a remote attacker to exfiltrate data from a compromised host.

The vulnerability exists due to inadequate filtering of the SSL handshake in Server Name Identification (SNI) request filtering. A remote attacker can use data from the SSL client hello packet to communicate with an external server and gain access to sensitive information on the target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

3000 Series Industrial Security Appliance (ISA): All versions

Cisco Firepower Threat Defense (FTD):

Cisco Web Security Appliance: All versions

Snort: 2.1.0 - 2.9.17.1

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sni-data-exfil-mFgzXqLN

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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.