CloudServices/Roadmaps/SimplePush-Server/SecCodeReview: Difference between revisions
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=== Architecture Diagram === | === Architecture Diagram === | ||
<a href="http://i.imgur.com/L5LC0tj"><img src="http://i.imgur.com/L5LC0tj.png"></a> | |||
External services, marked in yellow, communicate to the server which acts as a notification event proxy. | |||
=== Detailed Application Diagram === | === Detailed Application Diagram === | ||
Revision as of 19:28, 3 June 2013
Access Information
How is the application accessed?
Application is accessed in two ways. The client accesses via a WebSock connection. Third party servers access via a single REST PUT call.
Is the application internal or publicly available
This application is publicly available.
If it is internal, what mechanism prevents non-members from accessing it?
N/A
Are there links to user-only resources displayed to non-users?
No user information is displayed. In fact, very little information is actually stored or used in this application.
Are login pages secured with SSL over HTTPS?
There are no Login pages.
If HTTPS is used, is Strict Transport Security set?
Infrastructure and Backends
What languages do the applications use?
The application was written in Go.
What database language is used if applicable?
The application uses Memcache as a generic key/value data store.
Are the running versions up to date?
Currently running: go version devel +79a1fec35802 Fri May 24 12:37:42 2013 -0400 linux/amd64 memcached 1.4.13
What server is it running on?
Currently, the application is running on an AWS dev machine. ec2-54-244-98-201.us-west-2.compute.amazonaws.com (I can provide you general use ssh keys or you can provide a public key for OpsSec use.)
Accounts and Passwords
While there are technically "accounts" no password is maintained for these. UAIDs are generated by the client and used solely to identify itself to the server.
Update Information associated with a given client is stored as a pair of UUID4 values. A User Agent ID (UAID) and a ChannelID. There is an option for REST endpoint hashing which uses a simple,reversible AES hash to prevent third party sites from potentially gaining unwarranted information about the connecting clients.
Session Management
No Session cookies are used.
Third-Party Resources
Only third party resources are source libraries included in the binary application.
This code has been reviewed both by the golang community at large and by the local engineer.
Data Handling
What kind of data is transferred between the user and the application?
Client sends identifying UAID, and known channels (channels are ignored) Server returns list of channel updates for a given UAID (invalid channels are ignored by client) Third party server sends a PUT request to an Server generated endpoint triggering a channel update if valid, associated data for the PUT request is ignored.
Is this data generated by the user or generated automatically?
All data is programatically generated.
Can the data be trusted?
Generally, yes. Incoming data from the client is mostly ignored.
How is the data sent to the application (i.e. JSON format, plain-text, GET/POST, etc.)?
WebSocket uses JSON as the transport protocol.
How is the data handled by the server/application?
Server merely registers a self-expiring timestamp value in Memcache when a UAID.ChannelID pair is received.
Can the data be manipulated in transit?
Yes. Manipulation is irrelevant.
What happens if the data is altered?
Nothing. Client still receives the update.
What is done with the data once it is received (i.e. stored in a database, displayed to users)?
It is stored into Memcache, and then the client is notified if attached. If the client is not attached, an optional proprietary wake signal may be sent (out of band for this review) at which time the remote device may reconnect and accept the updates, sending an ACK message after receipt.
Is any data storage done via cookies? If so, what kind of data is stored via this method?
No.
Uploaded Data
There is no user meaningful data stored using this service.
Data Sensitivity
What kind of data is being stored and/or manipulated by the application?
A timestamp value is stored. This value is simply a placeholder as any data value could be used.
Does this data need to be encrypted in transit? In storage?
No.
What is the impact if this data is lost/stolen?
Someone just created a really annoying NNTP server.
Is secure/sensitive data sent over SSL?
No senstitive data is exchanged.
Application Administration
All real service management is performed locally by the client service. The server is gleefully ignorant of anything other than the user UAID.
Security Coding Flaws
Have all user inputs been sanitized?
Yes
Is a maximum size for data (input or uploads) defined?
No, data is discarded.
Do all URL variables pass through sanitization?
No, data is discarded.
Is data from databases escaped properly?
Yes
Are CSRF tokens used to prevent POSTs from outside websites?
POST values are not allowed.
If a database is used, are protections against SQL injection in place?
Database is not SQL based.
Is validation done on the server side (not just client-side)?
Data is discarded.
Is output encoded in addition to sanitization of input?
No.
Does the user ever send data to the OS level?
No.
Are x-frame options sent to “deny” or “sameorigin”?
No frames are used.
Is debug mode disabled?
Debugging merely increases logging output, and is controlled via server config options.
Additional Resources
Template for the above checks: https://docs.google.com/document/d/1SAzDuMwKUNN4_gdotqcv0oeZwLngjXjNYuZ2HZZaXp4/edit
Also, please view the WebAppSec Wiki: https://wiki.mozilla.org/WebAppSec
Security Review Documentation
Structure of a Security Review
This document covers five distinct activities and the documentation they produce when a security review is performed. Note that this guidance is prescriptive in that each component of a security review document should be produced, or a statement explaining why it wasn't should be included.
The goal of this document is to ensure that the Security Assurance team has a consistent format for the documentation we produce without enforcing a strict structure on how security review and testing is performed.
Architecture Diagram
<a href="http://i.imgur.com/L5LC0tj"><img src="
"></a>
External services, marked in yellow, communicate to the server which acts as a notification event proxy.
Detailed Application Diagram
A Detailed Application Diagram is essentially a Data-flow diagram; a data flow diagram enumerates each application or service that is a component of a system, and illustrates each of the paths data can flow through.
Note that a data-flow diagram is only one example of how this information. The goal is to effectively communicate to the audience how data moves through the system, where different operations are performed, and if detailed enough, how different roles within the system can access different operations.
When designing the detailed application diagram it can be useful to assemble a list of each of the subjects in a system.
TODO - add references for subject/object/operations in relation to access control models.
Key Attributes
- Clarity; labels for objects are brief, and contain clear references that can be used to cross-reference other documentation
- Detailed; ensure that all roles and operations are clearly presented
Additional Examples
Data-flow Enumeration
Data-flow enumeration is an important supplement to the Detailed Application Diagram; it acts as a reference for someone reading the diagram to look up the nature of what information is associated with a call or request between two components.
At a minimum, the flow enumeration should be a table indicating an identifier, subject, object, and the operation being performed.
In the example below, an excerpt from the BrowserID provisioning enumeration, the subject, object, and operation are labelled origin, destination, and description, respectively.
| ID | Origin | Destination | Description |
| 1.A | Relying Party | Implementation Provider | An interaction with the Relying party invokes the Implementation Provider (IP). |
| 1.B | Implementation Provider | Identity Authority | The IP either has an expired certificate, or no certificate, and directs the client to an Identity Authority landing page for authentication. This authentication process is out of scope of the protocol, and implementation dependent. |
| 1.C | Identity Authority | Identity Authority | Code from the IP landing page invokes genKeyPair() to generate a keypair. |
| 1.D | Identity Authority | Implementation Provider | The IP saves the keypair in the client |
In addition to including the subject, object, operation columns, it can be helpful to include an explicit list of fields which are considered sensitive.
Additional Examples
Threat Analysis
When performing a security review of an application one of the most important components is a threat analysis. There is a great deal of documentation on how to perform threat analysis, and a number of different techniques that can be used:
For the purposes of a Mozilla Security Review, the means by which someone identifies the threats and risks associated with an application is important, but not specified. If you have questions about how to perform this type of analysis, please contact a member of our team!
The resulting threat analysis should be formatted in a clear format, including the following details:
- ID - a identifier for the threat
- Title - a concise description of the threat
- Threat - a description of the threat
- Mitigations - a recommendation for a control that can be implemented [1]
- Threat Agent - a list of the potential actors considered that would exploit a vulnerability.
- Notes - Related comments that contribute to the analysis, but don't belong in other columns
- Rating - A qualitative scoring for a vulnerability in the context of this application [2]
- Impact - A qualitative score representing the impact should a vulnerability be exploited
- Likelihood - A qualitative score representing the likelihood of a vulnerability being exploited. [3]
See Risk Ratings for details of how to calculate the qualitative scores.
TODO - Glossary Threat, Threat Agent, Vulnerability, Exploit [1] In the case of a threat analysis that contains multiple threats that can be resolved by one or more different controls it may be beneficial to include a separate control table, and list references to controls in that table instead. [2] The rating is calculated by multiplying the impact by the likelihood. This is a naive method, but it's what we have! [3] In the case where different threat agents have different likelihoods, list the likelihoods highest to lowest, in the same order as the threat agents.
Below is an excerpt from the BrowserID Threat Analysis:
| ID | Title | Threat | Proposed Mitigations | Threat Agent | Rating | Likelihood | Notes | Impact | Notes |
| 1 | SIA may introduce compliance issues | Operating a Secondary Identity Authority may induce compliance requirements with regards to logging user information | Part of the goal of BrowserID is to have Primary Identity Authorities take on this risk as part of their other operations. This can be somewhat mitigated by eliminating support for the webfinger verification process. | Governments, Lawyers | 12 | 3 | Governments and other legal actors have the ability to request information from us, either through subpoenas, NSLs, etc. While we hold information that can link user identities to services this information will be a source of risk. | 4 – Reputation | Although we are required to comply, and Mozilla would fight such a request to the degree permitted, we would still receive negative press. |
| 2 | Webfinger Information Leak | Use of the webfinger service for verification discloses each authentication attempt from the Relying Party to the Identity Authority | Implement verification using certificates | Malicious Identity Authority | 25 | 5 | This information disclosure is a part of the protocol. | 5 – Privacy | This is probably a clear violation of our privacy policies. |
| 3 | Chrome Code Injection | Attacker controlled parameters could permit injection of script into browser chrome. | Ensure that any data controlled by the user or relying party is emitted using output encoding. | Malicious Relying Party, Malicious User, Malicious Identity Authority | 4 | 1 | Code review and testing should prevent this occuring. The technical complexity of this attack is higher than a vanilla XSS. | 4 – User | This gives an attacker the ability to execute code in the context of browser chrome. |
Additional Examples
Security Testing
The security test plan is a brief explanation of security testing that should be performed, and should include an explanation of what tasks are to be performed, and the approximate amount of time spent performing those tasks.