Sunday, 2 October 2016

systemd: OpenSSL of the future?

OpenSSL has received a lot of flak over the years. Both cryptographic and implementation flaws have been plentiful, and researchers are all over it. Much has been said about the software engineering process that was used to put it all together.

It appears to me that systemd is following a similar path, with another vulnerability turning up in the last few days. A very quick assessment of this vulnerability would place it as a 'medium' (CVSSv3 between 5.5 and 6.5) severity vulnerability. Ayer's post goes on to use this example as another data point in favour of the "systemd is insecure" camp.

OpenSSL is bad. It is security-critical software that has a constant stream of high and critical severity bugs. However, it's not too much of a problem for me. I update the library and restart the affected services of a test system, then on to the production systems. Usually this is just reloading or restarting nginx and sshd. The impact to end-users is small or non-existant. For some people, an OpenSSL bug is much worse, it all depends on the exact nature of the system you run and the particular bug.

On the other hand, we have systemd. We've not seen as many issues so far. But we can't just update and restart systemd, because it is a tightly integrated with many components. I feel like this is similar to the libc vulnerabilities we saw a little while back. The maintenance impact is much bigger because we're forced to do a full system restart.

This is one of the many reasons why privilege separation is such a good thing. Every new process gets the updated code. So while the minimal core of the application may contain vulnerable code, it might be easy to show that it is never reached. On the other hand, the privilege-separated workers don't need that much attention, so we just restart them and have them pick up the upgrades. Further, each worker process can be individually sandboxed and allowed to fail.

I agree with Ayer's perspective. Software is written by fallible humans who make mistakes with alarming regularity. When we dive into coding without thinking about the long-term implications, we set ourselves up for failure. If we build a monolith, any RCE bug is fatal. If we fail to sandbox our systems, any path traversal bug is fatal. We should avoid designs where common flaws are fatal.

Engineers need to be thinking about a few core questions:

  • How important is this system going to be?
  • How do we make bugs less likely?
  • How do we make bugs less problematic?
These are the central questions that a software development process answers. These are the questions which we frequently ignore. We purchase time-to-market with steep maintenance costs. If the systemd developers persist in ignoring these deeper issues, I think systemd will be the OpenSSL of the future. A constant stream of high and critical severity issues causing a never-ending headache for those that use it.

If you are starting a project, or running a project, please look at the design of vsftpd and OpenSSH. Look over the various secure software development life-cycles. Think about using a language that supports you. If you're going to push people to use your system, consider the security implications of your decisions and remember that hope is not a strategy.

Saturday, 2 January 2016

Top 5 Security Fails of 2015

Much like every other year, 2015 had a veritable smorgasbord of security breaches and failures. This top 5 list, in chronological order, catalogues the trials and tribulations of security in 2015.

Contributing author: Sephy Hallow.


Source: openclipart
This year opened with a bit of a bang, with CVE-2015-0235 being announced in January 2015. This vulnerability was branded as "GHOST." This was an issue with a core library which underlies almost every piece of Linux software. A successful attack would result in remote code execution on the target machine, gaining a CVSS score of 10.0 out of a possible 10.

The only saving grace was that it was difficult to determine if a particular piece of software actually used the library in a vulnerable way. As it turned out, very few pieces of software were actually vulnerable, but the difficulty determining that lead to a fair few people going into panic mode for a day or two.

Score: 1/5 - All Ghost and No Ghoulies

2. Office of Personnel Management

Source: Office of Personnel Management Seal
The Office of Personnel Management (OPM) breach was announced in June of 2015. Although the number of records exposed initially estimated at four million, this breach turned out to be a gift that kept on giving, with the estimate ballooning to 18 and finally 21.5 million records. Even better, the records were said to contain highly sensitive information from background checks, including personally identifying information, social security numbers, and even security clearance data.

What made this a real show stopper was the inept response. Putting aside the inability to simply count the number of records compromised, this became a comedy of errors as it was eventually shown that the OPM had been warned several times regarding shoddy security practices. In the aftermath of the attack, OPM set about trying to spread the blame far and wide, and speculated on the identity of the perpetrators rather than fixing their systems.

Score: 5/5 - Bureau Prats

3. Stagefright

Source: Charles Darwin

This year, no stone was left unturned, with security researchers turning their ingenuity to Android. Their efforts uncovered a glorious bounty of not one, not two, but eight vulnerabilities in a single library. Six of the eight vulnerabilities scored the maximum CVSS of 10.0 out of 10, with a 9.3 and a 5.0 thrown in for good measure. The vulnerabilities manifested themselves in the library named libstagefright, which was used for showing media files. A proof-of-concept exploit was developed which triggered the issue by the means of a crafted MMS message, and did not require user interaction.

Obviously, everyone quickly deployed the fix, right? Wrong. In reality we're talking about the Android ecosystem here, with the multiple phone carriers who are well known for not pushing security updates out to users. Oh, and the carriers lock the devices so that users cannot apply the patches themselves. Seems like a winning combination.

Score: 3/5 - Phantom of the Opera-ting System

4. Ashley Madison

Source: No Wedding
Not one to be out done on the sensitivity of information recovered, The Impact Team leaked some 25GB of customer data from Ashley Madison in August. Who is Ashley Madison, you ask? None other than that upstanding company who's motto is "Life is short. Have an affair." Clearly, their real motto was "Life is short. Security is for losers."

The data included roughly everything: financial information, names, addresses, and details of sexual fantasies. The internet took up harassing and bullying the victims whilst half the criminal underworld attempted to extort the victims. At least one person is known to have committed suicide, having directly cited the leak as their motivation for doing so.

Score: 5/5 - Security Blows

5. TalkTalk

Source: TalkTalk Logo
In October this year, TalkTalk's defences crumbled after coming under an alleged "significant and sustained cyber-attack" and purportedly leaked the details of some four million customers. Back in  reality, this was a simple SQL injection attack which could have been conducted by a relatively unskilled teenager in their bedroom. The attackers demanded a ransom of roughly £17 million. Eventually, TalkTalk revised their estimate of the number of records accessed down to approximately two hundred thousand, and the Metropolitan Police arrested a 15 year-old from Northern Ireland in connection with the breach.

After issuing a ransom demand and confusing the heck out of TalkTalk, the attackers either used or sold on the data, resulting in at least one victim losing nearly £3,000 to fraud. Finally, the CEO, Dido Harding, was hauled in front of a Home Affairs Select Committee and asked to account for TalkTalk's (in)actions regarding the incident, including allegations that they had "covered up both the scale and duration of this attack[.]" Nice.

Score: 3/5 - All Talk