安全研究

安全漏洞
Cisco IOS FTP Server非授权访问及远程控制漏洞

发布日期:2007-05-09
更新日期:2007-05-11

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: 23885
CVE(CAN) ID: CVE-2007-2586,CVE-2007-2587

Cisco IOS是Cisco网络设备所使用的操作系统。

Cisco IOS所带的FTP Server处理访问请求时存在漏洞,远程攻击者可能利用此漏洞非授权访问系统文件或获取对系统的控制。

启用了IOS FTP Server功能的Cisco IOS没有正确检查用户授权,可能允许攻击者非授权读写设备文件系统中的任意文件,包括设备保存的配置,其中可能有口令或其他敏感信息;此外这种配置的Cisco IOS还可能导致缓冲区溢出获取对IOS的控制。

<*来源:Cisco安全公告
  
  链接:http://secunia.com/advisories/25199/
        http://www.cisco.com/warp/public/707/cisco-sa-20070509-iosftp.shtml
*>

测试方法:

警 告

以下程序(方法)可能带有攻击性,仅供安全研究与教学之用。使用者风险自负!

http://www.milw0rm.com/exploits/6155

建议:
临时解决方法:

* 通过向设备配置中添加以下命令禁用IOS FTP Server功能:

    no ftp-server enable

* 选用其他文件传输方式,如安全拷贝(SCP)或使用简单文件传输协议(TFTP)服务器。
* 如下配置基础架构ACL(iACL):

    !--- Permit FTP services from trusted hosts destined
    !--- to infrastructure addresses.
    
    
    access-list 150 permit tcp TRUSTED_HOSTS MASK INFRASTRUCTURE_ADDRESSES MASK eq 21
    access-list 150 permit tcp TRUSTED_HOSTS MASK INFRASTRUCTURE_ADDRESSES MASK eq 20
    
    
    !--- Deny FTP packets from all other sources destined to infrastructure addresses.
    
    
    access-list 150 deny   tcp any INFRASTRUCTURE_ADDRESSES MASK eq 21
    access-list 150 deny   tcp any INFRASTRUCTURE_ADDRESSES MASK eq 20
    
    
    !--- Permit all other traffic to transit the device.
    
    
    access-list 150 permit IP any any
    
    interface serial 2/0
      ip access-group 150 in
      
* 如下配置接收ACL(rACL):

!--- Permit FTP from trusted hosts allowed to the RP.
    
    
    access-list 151 permit tcp TRUSTED_ADDRESSES MASK any eq 21
    access-list 151 permit tcp TRUSTED_ADDRESSES MASK any eq 20
    
    
    !--- Deny FTP from all other sources to the RP.
    
    
    access-list 151 deny   tcp any any eq 21
    access-list 151 deny   tcp any any eq 20
    
    
    !--- Permit all other traffic to the RP.
    !--- according to security policy and configurations.
    
    
    access-list 151 permit ip any any
    
    
    !--- Apply this access list to the 'receive' path.
    
    
    ip receive access-list 151

* 如下配置控制面板:

        access-list 152 deny   tcp TRUSTED_ADDRESSES MASK any eq 21
        access-list 152 deny   tcp TRUSTED_ADDRESSES MASK any eq 20
        access-list 152 permit tcp any any eq 20
        access-list 152 permit tcp any any eq 21
        access-list 152 deny    ip any any
        !
        class-map match-all COPP-KNOWN-UNDESIRABLE
         match access-group 152
        !
        !
        policy-map COPP-INPUT-POLICY
         class COPP-KNOWN-UNDESIRABLE
          drop
        !
        control-plane
         service-policy input COPP-INPUT-POLICY

厂商补丁:

Cisco
-----
Cisco已经为此发布了一个安全公告(cisco-sa-20070509-iosftp)以及相应补丁:
cisco-sa-20070509-iosftp:Multiple Vulnerabilities in the IOS FTP Server
链接:http://www.cisco.com/warp/public/707/cisco-sa-20070509-iosftp.shtml

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