PolarSSL Security Advisory 2013-04

Title	Buffer overflow in ssl_read_record()
CVE	CVE-2013-5914
Date	1st of October 2013 ( Updated on 8th of October 2013 )
Affects	PolarSSL versions prior to 1.1.8
Not affected	PolarSSL 1.2.0 and above
Impact	Possible remote exploit
Exploit	Withheld
Solution	Upgrade to PolarSSL 1.1.8, or 1.2.0 and later
Credits	independently found by both TrustInSoft and Paul Brodeur of Leviathan Security Group

When using TLS 1.1, ssl_read_record() omits to check the length of the incoming data. This results in a possible buffer overflow of the receive- buffer.

Only versions of PolarSSL prior to 1.1.8 are affected.

Impact

A third party can remotely trigger this buffer overflow by sending a packet with more data than SSL_BUFFER_LEN. This results in ssl_fetch_input() retrieving that amount of data into the input buffer.

Resolution

Upgrade to PolarSSL version 1.1.8, 1.2.9, 1.3.0 or try to apply the following patch.

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 27f2172..a5d1cb1 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1159,7 +1159,7 @@ int ssl_read_record( ssl_context *ssl )
         /*
          * TLS encrypted messages can have up to 256 bytes of padding
          */
-        if( ssl->minor_ver == SSL_MINOR_VERSION_1 &&
+        if( ssl->minor_ver >= SSL_MINOR_VERSION_1 &&
             ssl->in_msglen > ssl->minlen + SSL_MAX_CONTENT_LEN + 256 )
         {
             SSL_DEBUG_MSG( 1, ( "bad message length" ) );

Advice

We strongly advise you to consider upgrading to the 1.3 branch, or otherwise apply the patch, upgrade to version 1.1.8, 1.2.9 if outside parties are present or can connect to your network.