Web Admin Blog Real Web Admins. Real World Experience.

20May/150

SSH on a Mac Errors with “Write Failed: Broken Pipe”

Recently I had an issue when moving to a new Mac on OSX when I was trying to SSH to a Linux server.  It would make the initial connection and then prompt me for a password.  Once I entered the password, however, it would just hang (ctrl+c wouldn't even escape out) until eventually it would break to the command line with the message "Write Failed: Broken Pipe".  After digging through various posts online, most of which were referring to timing out due to inactivity, I finally found a winner.  I edited the /etc/sshd_config file and set the ClientAliveInterval value to 300.  Then, I rebooted my Mac.  The next time I tried to SSH to the same server, everything connected as expected.  I hope this helps someone else in the future who is running up against the same issue I had.

13Nov/090

OWASP Top 10 – 2010

This presentation was by Dave WIchers, COO of Aspect Security and an OWASP Board Member.  My notes are below:

What's Changed?

  • It's about Risks, not just vulnerabilities
    • New title is: "The Top 10 Most Critical Web Application Security Risks"
  • OWASP Top 10 Risk Rating Methodology
    • Based on the OWASP Risk Rating Methodology, used to prioritize Top 10
  • 2 Risks Added, 2 Dropped
    • Added: A6 - Security Misconfiguration
      • Was A10 in 2004 Top 10: Insecure Configuration Management
    • Added: A8 - Unvalidated Redirects and Forwards
      • Relatively common and VERY dangerous flaw that is not well know
    • Removed: A3 - Malicious File Execution
      • Primarily a PHP flaw that is dropping in prevalence
    • Removed: A6 - Information Leakage and Improper Error Handling
      • A very prevalent flaw, that does not introduce much risk (normally)
  1. A1- Injection: Tricking an application into including unintended commands in the data sent to an interpreter. (http://www.owasp.org/index.php/SQL_Injection_Prevention_Cheat_Sheet)
  2. A2 - Cross Site Scripting (XSS): Raw data from attacker is sent to an innocent user's browser.  For large chunks of user supplied HTML, use OWASP's AntiSamy to sanitize this HTML to make it safe.  (http://www.owasp.org/index.php/XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet)
  3. A3 - Broken Authentication and Session Management: Means credentials have to go with every request.  Should use SSL for everything requiring authentication.
  4. A4 - Insecure Direct Object Reference: This is part of enforcing proper "Authorization", along with A7 - Failure to Restrict URL Access.
  5. A5 - Cross Site Request Forgery (CSRF): An attack where the victim's browser is tricked into issuing a command to a vulnerable web application.  Vulnerability is caused by browsers automatically including user authentication data with each request.  (Check out OWASP CSRFGuard, OWASP CSRFTester, http://www.owasp.org/index.php/CSRF_Prevention_Cheat_Sheet)
  6. A6 - Security Misconfiguration: All through the network and platform.  Don't forget the development environment.  Think of all the places your source code goes.  All credentials should change in production.
  7. A7 - Failure to Restrict URL Access: This is part of enforcing proper "authorization", along with A4 - Insecure Direct Object References.
  8. A8 - Unvalidated Redirects and Forwards: Web application redirects are very common and frequently include user supplied parameters in the destination URL.  If they aren't validated, attacker can send victim to a site of their choice.
  9. A9 - Insecure Cryptographic Storage: Storing sensitive data insecurely.  Failure to identify all sensitive data.  Failure to identify all the places that this sensitive data gets stored.  Failure to properly protect this data in every location.
  10. A10 - Insufficient Transport Layer Protection

OWASP Top 10 Risk Rating Methodology

  • Attack Vector (How hard for an attacker to use this flaw - 1 (Easy), 2 (Average), 3 (Difficult))
  • Weakness Prevalence (How often is it found - 1 (Widespread), 2 (Common), 3 (Uncommon))
  • Weakness Detectability (How hard is it for an attacker to find the flaw - 1 (Easy),  2 (Average), 3 (Difficult))
  • Technical Impact (1 (Severe), 2 (Moderate), 3 (Minor))

This is generic across the internet, not specific to any organization.

Started a new "Prevention Cheatsheet Series" that the Top 10 references (XSS, SQL Injection, Transport Layer Security, CSRF, Direct Object Reference).

What is actually being released is RC1 of the Top 10 and they are encouraging people to provide comments through the end of the year and then use that feedback to post the final Top 10 in January 2010.