Hrvoje Niksic <hniksic@xxxxxxxxxx> writes:
> A fix that applies to 1.9.1 follows in a separate mail.
> Distributors of Wget will probably want to make sure to include the
> appropriate patch.
Here is that fix.
2005-05-07 Hrvoje Niksic <hniksic@xxxxxxxxxx>
* ftp-basic.c (ftp_request): Prevent newlines in VALUE causing
inadvertent sending of multiple FTP commands.
--- wget-1.9.1.pristine/src/ftp-basic.c 2003-11-08 20:17:55.000000000 +0100
+++ wget-1.9.1/src/ftp-basic.c 2005-05-07 03:08:02.306330903 +0200
@@ -116,9 +116,30 @@
static char *
ftp_request (const char *command, const char *value)
{
- char *res = (char *)xmalloc (strlen (command)
- + (value ? (1 + strlen (value)) : 0)
- + 2 + 1);
+ char *res;
+
+ /* Check for newlines in VALUE (possibly injected by the %0A URL
+ escape) making the callers inadvertently send multiple FTP
+ commands at once. Without this check an attacker could
+ intentionally redirect to ftp://server/fakedir%0Acommand.../ and
+ execute arbitrary FTP command on a remote FTP server. */
+ if (value && strpbrk (value, "\r\n"))
+ {
+ /* Copy VALUE to the stack and modify CR/LF to space. */
+ char *defanged, *p;
+ STRDUP_ALLOCA (defanged, value);
+ for (p = defanged; *p; p++)
+ if (*p == '\r' || *p == '\n')
+ *p = ' ';
+ DEBUGP (("\nDetected newlines in %s \"%s\"; changing to %s \"%s\"\n",
+ command, value, command, defanged));
+ /* Make VALUE point to the defanged copy of the string. */
+ value = defanged;
+ }
+
+ res = (char *)xmalloc (strlen (command)
+ + (value ? (1 + strlen (value)) : 0)
+ + 2 + 1);
sprintf (res, "%s%s%s\r\n", command, value ? " " : "", value ? value : "");
if (opt.server_response)
{
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