Interview with two phish-scene infiltrators

/. posted a link to this interview with Nitesh Dhanjani and Billy Rios, two guys who have infiltrated the “phishing underground”.

It’s a good article — lots of detail on the current toolset of a typical phisher, and some details on the community itself:

I had always thought that most phishers were clever hackers evading authorities using the latest evasion techniques and tools. The reality of the matter is most of the phishers we tracked were sloppy and unsophisticated. The tools they used were rarely created by the phisher deploying the actual scam, and for the most part it seemed the phisher merely downloaded kits and tools from some place and reused over and over and over again. It also seemed that many phishers don’t even really understand how the phishing kits they’ve deployed work! We also came across many phishing kits and tools that had simple backdoors written into the source code (essentially, phishers phishing phishers). These backdoors are easily spotted by anyone who has even a basic idea of how the source code flow worked, yet was undetected by many phishers. Maybe a few phishers out there are skilled, but the majority are clueless.

Here’s something I’ve noted about spammers, too — there’s no honour among thieves:

The number of backdoors we saw was staggering. The servers serving the phishing sites had backdoors, the code used in the phishing kits had backdoors, the tools used by phishers had backdoors. Phishers aren’t afraid to steal from regulars people and they are also not afraid to steal from other phishers. Some of the backdoors were meant to keep control over a compromised server, while other simply stole information that had been stolen by other phishers! We came across several forums where phishers, scammers, and carders basically identified other phishers, scammers, and carders that had scammed them. These shady characters may work with each other but they sure don’t trust each other, that’s for sure.

And this is a very important point about blacklists:

Phishers are likely to abuse the blacklists published for [anti-phishing] plugins for their own benefit. The blacklists are a list of known phishing sites that the plugins consume in order to identify what websites are fraudulent. These blacklists therefore contain IP addresses and host names of servers hosting phishing sites. Since phishing sites are commonly installed on servers that have been compromised, and phishers don’t bother to patch systems they have installed their kits on, this list translates to a ‘list of easily compromisable hosts’ for other phishers.

On the latter point, this is one of the key benefits of DNS blocklists, compared to the downloaded, text-based style that Google initially used for its anti-phishing toolbar. To query a DNSBL, you need to know the address you’re looking for first of all; but with a text file, you can read the lists in their entirety, without knowing the address in advance. (Google is now apparently tending to use the enchash format, which fixes this.)

And a final word:

For the next few years, we are going to continue to apply band-aids around the problem of data leakage, and continue to play whack-a-mole with the phishers without solving the actual problem at hand. In order to make any significant progress, we must come up with a brand new system that does away with depending on static identifiers. We will know weâ??ve accomplished this when we will be able to publish our credit reports publicly without fearing for our identities.

(I’d place more importance on the liability of the financial institutions, myself — I think they get away with placing too much blame on the victims of fraud and identity theft.)

Good interview — worth reading.

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Don’t use bl.spamcop.net as a blocklist

Update: as of Oct 2007, this advice is obsolete. The Spamcop algorithms have been greatly improved, as far as I and others can tell.

I’ve been hearing increasing reports of false positives using bl.spamcop.net.

One today spurred me to check out exactly how many times it I’m seeing it misfiring on nonspam in my own mail collection. The results have been pretty astonishing.

In my nonspam collection, it fired on 1043 messages out of 8415 in July; 12.4% of the mail. It gets worse for August, though — 884 messages out of 3729 since the start of August. That’s a staggering 23% of my nonspam mail this month. ;)

Most of that is due to the listings of GMail and Yahoo! Groups, both of which seem to have been listed for large swathes of the past month and a half.

Now, an important point — it can work pretty well as a single input to a scoring system, like Spamcop itself or SpamAssassin. In fact, I didn’t lose any mail as a result of those listings; SpamAssassin assigns only 1.5 points to the RCVD_IN_BL_SPAMCOP_NET rule, so it’s easily corrected by other rules.

However, people using it to block or reject spam outright, or who’ve changed the score of the RCVD_IN_BL_SPAMCOP_NET rule, need to turn that off ASAP — as they are losing mail.

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DnsblAccuracy082005 - Spamassassin Wiki

Do you use anti-spam DNS blocklists? If so, you should probably go take a look at DnsblAccuracy082005 on the SpamAssassin wiki; I’ve collated the results from our recent mass-check rescoring runs for 3.1.0, to produce have up-to-date measurements of the accuracy and hit-rates for most of the big DNS blocklists.

A few highlights:

We don’t have accurate figures for the new URIBL.COM lists, btw — only the rulesets that are distributed with SpamAssassin were measured.

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