OWASP Cheat Sheet Series

https://www.owasp.org/index.php/Cheat_Sheets

by aburan28 • 12 years ago

168 27 12 years ago

logn2• 12 years ago

On their Input Validation cheat sheet (https://www.owasp.org/index.php/Input_Validation_Cheat_Sheet) they recommend this as an example zip-code validation:

  ^\d{5}(-\d{4})?$

Depending on the language and regex interpreter options, this isn't as strict as it could be since it might accept unicode numbers. For the paranoid, this would be better:

  ^[0-9]{5}(-[0-9]{4})?$

Edit: And security issues aside, there's really no need for a capturing group on the last four digits, thus it could be:

    ^[0-9]{5}(?:-[0-9]{4})?$

mweibel2• 12 years ago

How about chars in zip codes (afaik GB has chars in zip codes)?

Input validation is usually a UX fail because there will be for sure one thing you miss (traditional example: email address validation). Zip codes I'd rather don't check at all or check against a list of valid zip codes if really necessary.

henrik_w• 12 years ago

As do Canadian ZIP-codes.

rmc2• 12 years ago

(afaik GB has chars in zip codes)

Yes the UK has letters in postcodes.

logn2• 12 years ago

Input validation is usually a UX fail

I agree in general. I think it was just a contrived example though in interest of discussing security/validation. Their example was in context of US users (and US zip-codes don't deviate from the pattern, but yes you could go one step further and reference the zip-code against the state and address using an API).

Also, specifically on regex, I'd imagine \d is being used in places where validation against unicode would be buggy (whether in form validation or elsewhere). I think Java and JavaScript default to ASCII only though.

jasonlotito2• 12 years ago

ZIP codes are an American thing. ZIP codes are a specific system of postal codes. If you are talking about ZIP codes, it's American.

If you are validating an American address, you'd want to validate using something that validates a ZIP code. If you get a Canadian address, you'd want to validate against that (which also happens to make it simple to validate against the province as well).

And yes, if you shouldn't using the term ZIP codes and postal codes interchangeably and treating them the same way in your code.

ctz2• 12 years ago

Every time I read something from OWASP, it has a bunch of glaring deficiencies, and appears to be an uneditable wiki. This time around:

Authentication_Cheat_Sheet: password rules which only apply to US-ASCII. That means people with non-US keyboards may not even be able to set a password which meet the rules (eg. Θ and ẞ are upper case, but does not count as upper case in their suggested rules).

Password_Storage_Cheat_Sheet: misses the critical step of unicode canonicalisation and encoding before feeding the password into the slow one-way function (which invariably take an octet string, not textual strings). If you fail to do this, your system will spuriously reject correct passwords if the user logs in via different devices or input methods.

Password_Storage_Cheat_Sheet: '32-bit or 64b' length salt is certainly too short to be called cryptographically strong. Particularly, a 32-bit salt is not enough to avoid leaking password equality with good probability between users once you get past the birthday bound.

Password_Storage_Cheat_Sheet: implies that the caller is responsible for prepending the salt to the credential before inputting it into the slow one-way function. That's not how PBKDF2, scrypt or bcrypt work.

hueving2• 12 years ago

Your assertion about the salt is wrong. That's not what a salt is designed to prevent. A salt is to prevent pregenerated tables from being meaningful, therefore 32-64bit is plenty.

'good probability' is a little dramatic too. The birthday paradox would only apply if every user had the same password to begin with. With 32 bits, you would need about 77000 users with the exact same password to get to 50% probability of two having the same salt/hash. 2000 users with the same password is 0.1% probability of two being the same.

If you are concerned about equalities because you have thousands of users with the same password, input the username into the hash generation function as well. Don't waste space with needlessly large salts.

ctz2• 12 years ago

Let's consider Adobe, since we have actual data. Of 130,324,429 users, we know 1,911,938 chose the password '123456'. Consider just that population of users.

Assume a 64-bit salt was chosen uniformly at random for each user. The probability that this cryptosystem is catastrophically broken (i.e. leaks password equality between users in just this population) is about 2^-23. That's not good -- usually cryptosystems are designed to have a probability of failure between 2^-80 and 2^-256. Now multiply that up for each population of users choosing the same password, and you're in trouble.

Adding in other user-unique data is definitely a good idea!

raesene2• 12 years ago

The wiki is not uneditable. You should be able to create an account, then you can edit pretty much any page on the site..

ams6110• 12 years ago

The guides may not be perfect (get a wiki account and improve them if you can) but they are better than most developers do, left to their own devices.

tptacek2• 12 years ago

I agree with you, in particular about the "password storage" stuff. OWASP has a particularly poor history of engaging with cryptography, and, because (I think) of the personalities involved, tend towards a "teach the controversy" approach anytime they're corrected.

theboss2• 12 years ago

Obviously OWASP can't be perfect. We may see the same security issues over and over but the details of particular problems will be specific to the code-base.

But stuff that is universal should be a lot better. Broken Auth page is so horrendous. They mention Broken-Auth then link to a 404 Session Management page, a white-paper on Session fixation, and a paper on password recovery.

It's bad. Instead of being a wikipedia where people can look up types of vulnerabilities, OWASP should try to have more pseudo-code or real code that developers can reference. They have some of this already but they need more

alexnewman• 12 years ago

As one of the original authors of clasp, I agree with the poster. We can do so much better. But it's important to realize these things move slow for a variety of reasons. Patches welcome.

davedx• 12 years ago

https://www.owasp.org/index.php/Web_Service_Security_Cheat_S... - ugh, "containers", SOAP and XML. Was hoping for something more general.

Fasebook• 12 years ago

or "How to make sure only the NSA can circumvent your security"

wglb• 12 years ago

One of the better examples of an OWASP cheat sheet is Rsnake's XSS: https://www.owasp.org/index.php/XSS_Filter_Evasion_Cheat_She....

tharri• 12 years ago

Does the fact that this site has "index.php" in all its URLs bother anyone else?

ADFASFGADA• 12 years ago

Nope not really. Probably only tards who can't seem to see that most of the successful web runs on PHP, not on their Brogrammer flavour-of-the-week language or framework.

e1ven• 12 years ago

I tend to be rather language agnostic, but URLs should generally be a descriptor of the content, and leak as few technological details as possible.

In general, having the URL include a specific implementation quirk, such as index.php makes it more difficult to have URLs that are stable years into the future, after you may have changed technology stacks.

OWASP Cheat Sheet Series

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