Ramblings of a Unix Geek

I've been doing this for a long time... I ramble!

Persistent Applications

A while ago I wrote about some of the technology basics that can be used for data persistency. Apparently this is becoming a big issue, so I’m revisiting this from another direction. Why does this matter? In essence, an application is a method of changing data from one state to another; “I charge $100 to my credit card” fires off a number of a number of applications that result in my account being debited, and the merchant being credited.

Multifactor Authentication

We’re all used to using passwords as an authenticator. However, passwords have a number of problems. In particular people tend to re-use them on other sites (so if one website was broken into the password used there may also work on another site). Also passwords are susceptible to replay attacks (even if you force a password change every 90 days, there’s still a large window of time where a stolen password can be used).

Encryption vs Hashing

Let’s say you run an ecommerce web site. As part of this people create accounts. Naturally those accounts have passwords. Do you encrypt those passwords before storing them in the database? All you people who put your hands up and answered yes… put them down; you’re wrong. You should hash the data instead. This may sound like a “tomato/tomato” thing, but it’s not. Encryption and hashing may both be cryptographic in nature, but there’s a subtle difference between them.

Role Based Access Control

Identity and Access Management (IAM) historically consists of the three A’s Authentication What acccount is being accessed? Authorization Is this account allowed access to this machine? Access Control What resources are you allowed to use? Companies spend a lot of time and effort on the Authentication side of the problem. Single signon solutions for web apps, Active Directory for servers (even Unix machines), OAuth for federated access to external resources, 2 Factor for privileged access… there’s a lot of solutions around and many companies know what they should be doing, here.

Lessons from a pentest run

Over on Twitter, @TinkerSec live tweeted a pentest and created a moment thread of it. It’s fascinating reading, and well worth reading. Even non-technical people should be able to get something out of this. I like that it’s a form of insider attack (industrial espionage by a newly hired employee? disgruntled employee? vendor allowed unaccompanied access?) rather than an external attack. One of the things that typically comes out of an event like this is a series of action items.

Phishing and Certificate Transparency

Many people are at a large risk of a phishing attack. In this scenario the person may receive an email that looks like it came from a legitimate source (e.g. their bank) and encourages them to click a link that presents them with their bank login page. The user then attempts to login… Except that site isn’t their banking site. It’s a mockup that looks like the real one. And they’ve now told their banking password to the attacker.

Offsite Backups in the cloud

Part of any good backup strategy is to ensure a copy of your backup is stored in a secondary location, so that if there is a major outage (datacenter failure, office burns down, whatever) there is a copy of your data stored elsewhere. After all, what use is a backup if it gets destroyed at the same time as the original? A large enterprise may do cross-datacenter backups, or stream them to a “bunker”; smaller business may physically transfer media to a storage location (in my first job mumble years ago, the finance director would take the weekly full-backup tapes to her house so we had at most 1 week of data loss).

Abusing LD_PRELOAD for fun and profit

The ELF format is pretty common across various unix versions, having superseded previous binary formats such as a.out and COFF. Pretty much, today, if you see a unix binary then it’s probably ELF format. One of features of the ELF format is that the run time linker can be smart about how it resolves dependencies, and this smartness can be tuned. A typical tuning many people know is the LD_LIBRARY_PATH variable, which can be used to add new directories to be searched for the needed libraries.

Can you control the entry points to your network?

One of the major threats that companies are concerned about is “insider threat”. According to some Data Breach Incident Response (DBIR) analyses, insider threat may be the 2nd or 3rd major reason for data loss. It’s interesting to note that the insider threat is way down in the actual number of incidents, but they count for a larger number of successful data loss incidents because the insider knows where the data is, may have legitimate access to the data, and may know the controls that need to be bypassed to exfiltrate it.

Managing the cloud management layer

A typical cloud engagement has a dual responsibility model. There’s stuff that can be considered “below the line” and is the responsibility of the cloud service provider (CSP) and there’s stuff above the line, which is the responsibility of the customer. Amazon have a good example for their IaaS: Where the line lives will depend on the type of engagement; the higher up the abstraction tree (IaaS->PaaS->SaaS) the more the CSP has responsibility.