Cisco 操作系统IOS存在DLSw拒绝服务漏洞

Cisco IOS在处理UDP和IP 91协议报文时存在多个漏洞，这些漏洞不影响TCP报文处理，成功攻击可能导致系统重启或设备内存泄露，造成拒绝服务的情况。
发布日期：2008-03-26 更新日期：2008-04-08 受影响系统： Cisco IOS 12.4 Cisco IOS 12.3 Cisco IOS 12.2 Cisco IOS 12.1 Cisco IOS 12.0 描述： -------------------------------------------------------------------------------- BUGTRAQ ID: 28465 CVE(CAN) ID: CVE-2008-1152 Cisco IOS是思科网络设备中所使用的互联网操作系统。 数据-链路交换（DLSw）允许通过IP网络传输IBM系统网络架构（SNA）和网络基本输入/输出系统（NetBIOS）通讯。Cisco的DLSw实现还使用UDP 2067端口和IP 91协 议进行快速顺序传输（FST）。 Cisco IOS在处理UDP和IP 91协议报文时存在多个漏洞，这些漏洞不影响TCP报文处理，成功攻击可能导致系统重启或设备内存泄露，造成拒绝服务的情况。 <*来源：Cisco安全公告 链接：http://secunia.com/advisories/29507/ http://www.cisco.com/warp/public/707/cisco-sa-20080326-dlsw.shtml http://www.us-cert.gov/cas/techalerts/TA08-087B.html *> 建议： -------------------------------------------------------------------------------- 临时解决方法： * 如下配置iACL
!--- Permit DLSw (UDP port 2067 and IP protocol 91) packets
!--- from trusted hosts destined to infrastructure addresses.

access-list 150 permit udp TRUSTED_HOSTS MASK INFRASTRUCTURE_ADDRESSES MASK eq 2067
access-list 150 permit 91 TRUSTED_HOSTS MASK INFRASTRUCTURE_ADDRESSES MASK

!--- Deny DLSw (UDP port 2067 and IP protocol 91) packets from
!--- all other sources destined to infrastructure addresses.

access-list 150 deny udp any INFRASTRUCTURE_ADDRESSES MASK eq 2067
access-list 150 deny 91 any INFRASTRUCTURE_ADDRESSES MASK

!--- Permit/deny all other Layer 3 and Layer 4 traffic in accordance
!--- with existing security policies and configurations
!--- Permit all other traffic to transit the device.

access-list 150 permit ip any any
interface serial 2/0
ip access-group 150 in
* 如下配置控制面整形（CoPP）
!--- Deny DLSw traffic from trusted hosts to all IP addresses
!--- configured on all interfaces of the affected device so that
!--- it will be allowed by the CoPP feature

access-list 111 deny udp host 192.168.100.1 any eq 2067
access-list 111 deny 91 host 192.168.100.1 any

!--- Permit all other DLSw traffic sent to all IP addresses
!--- configured on all interfaces of the affected device so that it
!--- will be policed and dropped by the CoPP feature

access-list 111 permit udp any any eq 2067
access-list 111 permit 91 any any

!--- Permit (Police or Drop)/Deny (Allow) all other Layer 3 and Layer 4
!--- traffic in accordance with existing security policies and
!--- configurations for traffic that is authorized to be sent
!--- to infrastructure devices
!--- Create a Class-Map for traffic to be policed by
!--- the CoPP feature

class-map match-all drop-DLSw-class
match access-group 111

!--- Create a Policy-Map that will be applied to the
!--- Control-Plane of the device.

policy-map drop-DLSw-traffic
class drop-DLSw-class
drop

!--- Apply the Policy-Map to the Control-Plane of the
!--- device

control-plane
service-policy input drop-DLSw-traffic
请注意在Cisco IOS 12.2S和12.0S系列中policy-map句法有所不同：
policy-map drop-DLSw-traffic
class drop-DLSw-class
police 32000 1500 1500 conform-action drop exceed-action drop
厂商补丁： Cisco ----- Cisco已经为此发布了一个安全公告（cisco-sa-20080326-dlsw）以及相应补丁: cisco-sa-20080326-dlsw：Multiple DLSw Denial of Service Vulnerabilities in Cisco IOS 链接：http://www.cisco.com/warp/public/707/cisco-sa-20080326-dlsw.shtml