On Sun, Jul 04, 1999 at 01:38:48PM +0200, Michal Zalewski wrote: > ---------------------------- > wu-ftpd 2.5, VR and BeroFTPD > ---------------------------- > > Compromise: remote root > > Solution: add strlen() check somewhere > > There's an overflow in wu-ftpd 2.5 and prior releases (including VR and > BeroFTPD) in mapped_path when mapping current working directory to > command-line. While I discovered this vunerability by myself, I don't want > to provide exploit code, as all other, hard work has been done > independently by someone else. Instead of that, there's a .diff file with > patch, attached somewhere as ftpd.diff. The Debian package of wu-ftpd (2.5.0-3) has just been updated with this patch: --- wu-ftpd-2.5.0.orig/src/ftpd.c +++ wu-ftpd-2.5.0/src/ftpd.c @@ -1243,9 +1246,12 @@ } /* append the dir part with a leading / unless at root */ - if( !(mapped_path[0] == '/' && mapped_path[1] == '\0') ) - strcat( mapped_path, "/" ); - strcat( mapped_path, dir ); + if ( strlen( mapped_path ) + strlen( dir ) < MAXPATHLEN-2 ) { + if( !(mapped_path[0] == '/' && mapped_path[1] == '\0') ) + strcat( mapped_path, "/" ); + strcat( mapped_path, dir ); + } else + syslog( LOG_ERR, "mapped_path overflow: possible exploit attempt" ); } int Correct me if I'm wrong, but it doesn't seem that the wu-ftpd Academ betas (specifically beta 16, included in Debian 2.1 (slink)) are vulnerable. Thus I doubt that our security team will issue an advisory, because this version is present only in the unstable distribution. -- enJoy -*/\*- don't even try to pronounce my first name
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