Vulnerabilidades Cisco PIX e ASA

Categoria: Alertas

quinta, 03 maio 2007 17:07

Sistemas Operativos Implicados:	Cisco IOS
Aplicações Implicadas:	Indefinido

Foram reportadas várias vulnerabilidades para Cisco PIX e ASA, estas podem ser exploradas por actos maliciosos para ultrapassar determinadas medidas de segurança ou para causar DoS (Denial of Service). A Cisco anunciou um boletim de segurança com informação detalhada sobre as mesmas. São destacadas duas vulnerabilidades que afectam a autenticação LDAP(Lightweight Directory Access Protocol), e outras duas relacionadas com VPNs (Virtual Private Networks ).

I. Descrição

Some vulnerabilities have been reported in Cisco PIX and ASA, which can be exploited by malicious people to bypass certain security restrictions or cause a DoS (Denial of Service).

1) An unspecified error exists when using the LDAP authentication mechanism, which can be exploited to bypass the authentication and gain access to the device or the network.

Successful exploitation requires that the device uses the Layer 2 Tunneling Protocol (L2TP) and is configured to use LDAP servers with another protocol other than PAP for authentication, or that the device offers remote management access (telnet, SSH, HTTP) and uses an LDAP AAA server for authentication.

2) An unspecified error when using VPN connections configured with password expiry can be exploited to cause a DoS.

Successful exploitation requires that the tunnel group is configured with password expiry. In order to exploit this in IPSec VPN connections, an attacker also needs to know the group name and group password.

3) A race condition within the processing of non-standard SSL sessions in the SSL VPN server of Cisco ASA appliances can be exploited to cause the device to reload.

Successful exploitation requires that clientless SSL is used.

4) An error within the DHCP relay agent when handling DHCPACK messages can be exploited to cause a DoS due to memory exhaustion by sending a large number of DHCP requests to a vulnerable device.

Successful exploitation requires that devices are configured to use the DHCP relay agent.

Solution:
Apply updated software versions. Please see vendor advisories for details.

Provided and/or discovered by:
1-3) Reported by the vendor.
4) Lisa Sittler and Grant Deffenbaugh, CERT/CC.

Original Advisory:
Cisco:
http://www.cisco.com/warp/public/707/cisco-sa-20070502-asa.shtml
http://www.cisco.com/warp/public/707/cisco-sr-20070502-pix.shtml

http://www.cisco.com/en/US/products/p...ecurity_response09186a0080833172.html
http://www.cisco.com/en/US/products/p...ligence_response09186a008083316f.html

US-CERT VU#530057:
http://www.kb.cert.org/vuls/id/530057

Other References:
US-CERT VU#210876:
http://www.kb.cert.org/vuls/id/210876

US-CERT VU#337508:
http://www.kb.cert.org/vuls/id/337508

II. Referências

Secunia:
http://secunia.com/advisories/25109/

US-CERT:
http://www.us-cert.gov/current/index.html#cisco_releases_security_advisory_to1