Cisco Systems has addressed flaws in its Adaptive Security
Appliance (ASA) and PIX security appliances attackers could exploit
to cause a denial of service or bypass authentication.
The networking giant said the flaws include two Lightweight
Directory Access Protocol
(
LDAP) authentication bypass vulnerabilities and two
denial-of-service vulnerabilities. Cisco PIX and ASA appliances
provide firewall, intrusion detection, VPN and secure connectivity
services.
"The LDAP authentication bypass vulnerabilities are caused by a
specific processing path followed when the device is set up to use
a LDAP authentication server,"
Cisco said in an advisory. "These
vulnerabilities may allow unauthenticated users to access either
the internal network or the device itself."
The two denial-of-service flaws may be triggered when devices
terminate VPNs, the vendor added. These denial-of-service
vulnerabilities may allow an attacker to disconnect VPN users,
prevent new connections or prevent the device from transmitting
traffic.
"These vulnerabilities are distributed in the authentication,
IPSec VPN, and SSL VPN code," Cisco said, adding that it has
released free software to fix the flaws.
The flaws are serious enough that
the
United States Computer Emergency Readiness Team (US-CERT)
released its own advisory, warning that a remote attacker could
gain unauthorized access to the internal network or firewall.
Antivirus giant Symantec also issued a warning to customers of
its DeepSight threat management service, saying that to exploit any
of these issues, an attacker scans for and locates a vulnerable
device. To exploit a denial-of-service vulnerability, the attacker
constructs specially crafted network data that can trigger the
issue, and then sends it to the affected device. When the data is
received and processed by the affected device, it will cause the
device to reload, Symantec added.
To exploit the authentication-bypass vulnerability, Symantec
said the attacker can construct malicious network traffic and send
it to the affected device, bypassing its authentication
mechanism.