Null passwords can lead to confusion in the code.
It is not a good idea to have a null password.
Example: The following code sets the password to initialy to null:
...
var password=null;
...
{
password=getPassword(user_data);
...
}
...
if(password==null){
// Assumption that the get didn't work
...
}
...
[1] Standards Mapping - OWASP Top 10 2010 - (OWASP 2010) A7 Insecure Cryptographic Storage
[2] Standards Mapping - OWASP Top 10 2007 - (OWASP 2007) A8 Insecure Cryptographic Storage
[3] Standards Mapping - OWASP Top 10 2004 - (OWASP 2004) A8 Insecure Storage
[4] Standards Mapping - Security Technical Implementation Guide Version 3 - (STIG 3) APP3210.1 CAT II, APP3340 CAT I, APP3350 CAT I
[5] Standards Mapping - Common Weakness Enumeration - (CWE) CWE ID 259
[6] Standards Mapping - FIPS200 - (FISMA) IA
[7] Standards Mapping - SANS Top 25 2009 - (SANS 2009) Porous Defenses - CWE ID 259
[8] Standards Mapping - Payment Card Industry Data Security Standard Version 1.2 - (PCI 1.2) Requirement 3.4, Requirement 6.3.1.3, Requirement 6.5.8, Requirement 8.4
[9] Standards Mapping - Payment Card Industry Data Security Standard Version 2.0 - (PCI 2.0) Requirement 3.4, Requirement 6.5.3, Requirement 8.4
[10] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 - (PCI 1.1) Requirement 3.4, Requirement 6.5.8, Requirement 8.4