发布时间 :2000-12-11 00:00:00
修订时间 :2008-09-05 16:22:27

[原文]The mailguard feature in Cisco Secure PIX Firewall 5.2(2) and earlier does not properly restrict access to SMTP commands, which allows remote attackers to execute restricted commands by sending a DATA command before sending the restricted commands.

[CNNVD]Cisco Secure PIX Firewall漏洞(CNNVD-200012-055)

        Cisco Secure PIX Firewall 5.2(2)及其早期版本的mailguard特性不能正确限制访问到STMP命令。远程攻击者通过在发送限制命令之前发送DATA命令执行限制命令。

- CVSS (基础分值)

CVSS分值: 7.5 [严重(HIGH)]
机密性影响: PARTIAL [很可能造成信息泄露]
完整性影响: PARTIAL [可能会导致系统文件被修改]
可用性影响: PARTIAL [可能会导致性能下降或中断资源访问]
攻击复杂度: LOW [漏洞利用没有访问限制 ]
攻击向量: [--]
身份认证: NONE [漏洞利用无需身份认证]

- CPE (受影响的平台与产品)


- OVAL (用于检测的技术细节)


- 官方数据库链接
(官方数据源) MITRE
(官方数据源) NVD
(官方数据源) CNNVD

- 其它链接及资源
(VENDOR_ADVISORY)  XF  cisco-pix-smtp-filtering
(UNKNOWN)  CISCO  20001005 Cisco Secure PIX Firewall Mailguard Vulnerability
(UNKNOWN)  BUGTRAQ  20000920 Re: Cisco PIX Firewall (smtp content filtering hack) - Version 4.2(1) not exploitable
(UNKNOWN)  BUGTRAQ  20000919 Cisco PIX Firewall (smtp content filtering hack)

- 漏洞信息

Cisco Secure PIX Firewall漏洞
高危 未知
2000-12-11 00:00:00 2005-05-02 00:00:00
        Cisco Secure PIX Firewall 5.2(2)及其早期版本的mailguard特性不能正确限制访问到STMP命令。远程攻击者通过在发送限制命令之前发送DATA命令执行限制命令。

- 公告与补丁


- 漏洞信息 (20231)

Cisco PIX Firewall 4.x/5.x SMTP Content Filtering Evasion Vulnerability (EDBID:20231)
hardware remote
2000-09-19 Verified
0 Lincoln Yeoh
N/A [点击下载]

Like other firewalls, the Cisco PIX Firewall implements technology that reads the contents of packets passing through it for application-level filtering. In the case of SMTP, it can be configured so only certain smtp commands can be allowed through (for example, dropping extra functionality, such as HELP or commands that could be a security concern, like EXPN or VRFY). When recieving messages, it allows all text through between "data" and "<CR><LF><CR><LF>.<CR><LF>", as this is where the body of the message would normally go and there could be words in it that are smtp commands which shouldn't be filtered. Due to the nature of SMTP and flaws in exceptional condition handling of PIX, it is reportedly possible to evade the smtp command restrictions by tricking the firewall into thinking the body of the message is being sent when it isn't.

During communication with an smtp server, if the "data" command is sent before the more important information is sent, such as "rcpt to", the smtp server will return error 503, saying that rcpt was required. The firewall, however, thinks everything is alright and will let everything through until recieving "<CR><LF><CR><LF>.<CR><LF>". It is then possible for the attacker to do whatever he wishes on the email server. 

Here an example of what i could do exploiting this bug:
helo ciao
mail from:
data ( From here pix disable fixup)
expn guest ( Now i could enumerate user
vrfy oracle and have access to all command)
whatever command i want

- 漏洞信息

Cisco PIX Firewall Mailguard Feature SMTP Content Filter Bypass Remote SMTP Command Execution
Remote / Network Access Input Manipulation
Loss of Integrity Upgrade
Exploit Public Vendor Verified, Third-party Verified

- 漏洞描述

- 时间线

2000-09-19 Unknow
Unknow 2000-09-27

- 解决方案

Upgrade to the latest version as of 2000-09-27, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.

- 相关参考

- 漏洞作者

Unknown or Incomplete