Summary
There is a severe bug in racoon's authentication via digital
signatures with certificates.
Description
racoon verifies the peer's certificate using eay_check_x509cert().
For some strange reason eay_check_x509cert() sets a verify callback:
X509_STORE_set_verify_cb_func(cert_ctx, cb_check_cert);
Verify callbacks are usually used for debugging purpose. Take a look
at what racoon uses the verify callback for:
static int
cb_check_cert(ok, ctx)
int ok;
X509_STORE_CTX *ctx;
{
char buf[256];
int log_tag;
if (!ok) {
[..]
switch (ctx->error) {
case X509_V_ERR_CERT_HAS_EXPIRED:
case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
#if OPENSSL_VERSION_NUMBER >= 0x00905100L
case X509_V_ERR_INVALID_CA:
case X509_V_ERR_PATH_LENGTH_EXCEEDED:
case X509_V_ERR_INVALID_PURPOSE:
#endif
ok = 1;
log_tag = LLV_WARNING;
break;
default:
log_tag = LLV_ERROR;
}
[..]
}
ERR_clear_error();
return ok;
}
If OpenSSL fails on verifying the certificate, because it is expired,
self-signed, signed by an inappropriate CA, not allowed for that
purpose or the certificate chain is too long, racoon does not care
about that and declares the verification successful. I dare to say
that is brain dead.
Affected Systems
All version of racoon known to me are vulnerable.
Impact
IMO besides remote privilege escalation that is the worst case
scenario for an IKE daemon.
Solution?
There are no bug fixes, yet. I recommend not using racoon at all.
Thomas Walpuski
