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：

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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/

*>

建议：

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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：