KAME Racoon May Validate Invalid Certificates
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SecurityTracker Alert ID: 1010495
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SecurityTracker URL: http://securitytracker.com/id?1010495
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CVE Reference: CAN-2004-0607
(Links to External Site)
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OSVDB Reference: 7113
(Links to External Site)
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Updated: Jul 30 2004
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Original Entry Date: Jun 15 2004
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Impact: Host/resource access via network
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Description: A vulnerability was reported in KAME Racoon. The software may validate invalid certificates in certain cases.
Thomas Walpuski reported that there is a flaw in the verification of digital certificates in the eay_check_x509cert() function.
The function sets a verify callback that will result in a successful verification on certificates that have expired, are self-signed,
signed by an invalid certificate authority, used for an invalid purpose, or have a certificate chain that is too long, the report
said.
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Impact: Invalid certificates may be successfully validated.
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Solution: No solution was available at the time of this entry.
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Vendor URL: www.kame.net/racoon/ (Links to External Site)
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Cause: Authentication error, State error
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Underlying OS: Linux (Any), UNIX (Any)
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Reported By: Thomas Walpuski <thomas-fd@unproved.org>
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Mon, 14 Jun 2004 18:55:11 +0000
From: Thomas Walpuski <thomas-fd@unproved.org>
Subject: [Full-Disclosure] authentication bug in KAME's racoon
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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
_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.netsys.com/full-disclosure-charter.html
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