Last Updated: 2014-04-08 20:23:51 UTC
by Johannes Ullrich (Version: 2)
(this article is work in progress and will be updated as we have new information. Also see the comments for links to signatures and other information provided by readers)
We decided to go to Infocon Yellow to alert readers of this vulenrability.
For those of you using OpenSSL 1.0.1 (most recent Unix systems), it is critical that you patch the openssl library, as well as binaries compiled statically with openssl, as soon as possible. 
The attack will allow a remote attacker to read up to 64kBytes of system memory from your system per attack attempt. The attack works against servers as well as against clients. While not all software using SSL necessarily uses the OpenSSL library, many do. (see our prior diary)
A proof of concept exploit has been made available and I have tested it. It can be used to remotely scan for vulnerable systems.  We have not yet detected wide spread use of the exploit, but it is literally hours old. At this point, we don't think the vulnerability was known in the underground before the official release, but it is possible.
What should you do first:
Check if you are vulnerable. "openssl version -a" will return the version information. If your version is 1.0.1, you MAY be vulnerable. Only version 1.0.1g is NOT vulnerable. Other major versions (0.9x, 1.0.0 ...) are not vulnerable.
Rule of thumb: If you are using OpenSSL, and if you are supporting TLS 1.2 (check ssllabs.com) , then you are vulnerable unless patched.
If I am vulnerable, what should I do:
Patch! Ubuntu, CentOS and others have patches available. OS X Mavericks has NO PATCH available. Windows is likely not vulnerable, but if you are running open source software like Apache that uses OpenSSL, then you may be vulnerable.
You may want to consider replacing SSL certificates if you are afraid that the exploit was already used against your site. But the exploit is not limited to secret SSL key. All data in memory is potentially at risk.
Can I test remotely?
The PoC exploit above can be used to scan your network remotely.
How Can I Tell if Someone is Using the Exploit Against Me
We don't have IDS signatures (yet... wait for updates here). There is no log entry in your web server log as the exploit happens after the SSL session is established, and before the HTTP request is sent.
nginx, after being patched, logs the following from the PoC exploit:
2014/04/08 12:37:18 [info] 4151#0: *724561 peer closed connection in SSL handshake while SSL handshaking, client: 126.96.36.199, server: 0.0.0.0:8443
Last Updated: 2014-04-08 20:23:09 UTC
by Richard Porter (Version: 3)
Overview of the April 2014 Microsoft patches and their status.
|#||Affected||Contra Indications - KB||Known Exploits||Microsoft rating(**)||ISC rating(*)|
Vulnerabilities in Microsoft Word and Office Web Apps Could Allow Remote Code Execution
(Replaces MS14-001 )
Cumulative Security Update for Internet Explorer
(Replaces MS14-012 )
Vulnerability in Windows File Handling Component Could Allow Remote Code Execution
(Replaces MS12-081 )
Vulnerability in Microsoft Publisher Could Allow Remote Code Execution
(Replaces MS13-042 )
We appreciate updates
US based customers can call Microsoft for free patch related support on 1-866-PCSAFETY
We use 4 levels:
- PATCH NOW: Typically used where we see immediate danger of exploitation. Typical environments will want to deploy these patches ASAP. Workarounds are typically not accepted by users or are not possible. This rating is often used when typical deployments make it vulnerable and exploits are being used or easy to obtain or make.
- Critical: Anything that needs little to become "interesting" for the dark side. Best approach is to test and deploy ASAP. Workarounds can give more time to test.
- Important: Things where more testing and other measures can help.
- Less Urgent: Typically we expect the impact if left unpatched to be not that big a deal in the short term. Do not forget them however.
- The difference between the client and server rating is based on how you use the affected machine. We take into account the typical client and server deployment in the usage of the machine and the common measures people typically have in place already. Measures we presume are simple best practices for servers such as not using outlook, MSIE, word etc. to do traditional office or leisure work.
- The rating is not a risk analysis as such. It is a rating of importance of the vulnerability and the perceived or even predicted threat for affected systems. The rating does not account for the number of affected systems there are. It is for an affected system in a typical worst-case role.
- Only the organization itself is in a position to do a full risk analysis involving the presence (or lack of) affected systems, the actually implemented measures, the impact on their operation and the value of the assets involved.
- All patches released by a vendor are important enough to have a close look if you use the affected systems. There is little incentive for vendors to publicize patches that do not have some form of risk to them.
(**): The exploitability rating we show is the worst of them all due to the too large number of ratings Microsoft assigns to some of the patches.
Last Updated: 2014-04-08 11:14:02 UTC
by Guy Bruneau (Version: 1)
OpenSSL 1.0.1g has been released to fix "A missing bounds check in the handling of the TLS heartbeat extension can be used to reveal up to 64kB of memory to a connected client or server. This issue did not affect versions of OpenSSL prior to 1.0.1." known as the Heartbleed Bug .
/*** update by Johannes Ullrich ...: ***/
Ubuntu released a patch for affected versions:
Ubuntu also updated OpenSSH.
CentOS/RHEL has a patch available.
For CentOS, the OpenSSL version did not change. Instead, only the compile time changed. To test if you are running the right version, look at the second line of the "openssl version -a" output:
The quickest way to figure out which version of OpenSSL you are using is:
openssl version -a
But not that some software may be compiled statically with openssl.
For a vulnerable system, this will return a version of 1.0.1f (or anything but 'g'). Also there will be no complier flag-DOPENSL_NO_HEARTBEATS.
For example, on a current OS X Mavericks system, you will get:
$ openssl version -a
OpenSSL 1.0.1f 6 Jan 2014
built on: Mon Jan 6 23:30:17 PST 2014
options: bn(64,64) rc4(ptr,char) des(idx,cisc,16,int) idea(int) blowfish(idx)
compiler: /usr/bin/clang -fPIC -fno-common -DOPENSSL_PIC -DZLIB -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -arch x86_64 -O3 -DL_ENDIAN -Wall -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM
Guy Bruneau IPSS Inc. gbruneau at isc dot sans dot edu