1679
Weakness ID : 790
Structure : Simple
Abstraction : Class
Description
The product receives data from an upstream component, but does not filter or incorrectly filters
special elements before sending it to a downstream component.
Relationships
The table(s) below shows the weaknesses and high level categories that are related to this
weakness. These relationships are defined as ChildOf, ParentOf, MemberOr and give insight to
similar items that may exist at higher and lower levels of abstraction. In addition, relationships such
as PeerOf and CanAlsoBe are defined to show similar weaknesses that may want to be explored.
Relevant to the view "Research Concepts" (CWE-1000)
Nature Type ID Name Page
ChildOf 138 Improper Neutralization of Special Elements 373
ParentOf 791 Incomplete Filtering of Special Elements 1680
Relevant to the view "Architectural Concepts" (CWE-1008)
Nature Type ID Name Page
MemberOf 1019 Validate Inputs 2433
Common Consequences
Scope Impact Likelihood
Integrity Unexpected State
Demonstrative Examples
Example 1:
The following code takes untrusted input and uses a regular expression to filter "../" from the input.
It then appends this result to the /home/user/ directory and attempts to read the file in the final
resulting path.
Example Language: Perl (Bad)
my $Username = GetUntrustedInput();
$Username =~ s/\.\.\///;
my $filename = "/home/user/" . $Username;
ReadAndSendFile($filename);
Since the regular expression does not have the /g global match modifier, it only removes the first
instance of "../" it comes across. So an input value such as:
Example Language: (Attack)
../../../etc/passwd
will have the first "../" stripped, resulting in:
Example Language: (Result)
../../etc/passwd
This value is then concatenated with the /home/user/ directory:
CWE Version 4.14
CWE-791: Incomplete Filtering of Special Elements
CWE-791: Incomplete Filtering of Special Elements