| Name |
Accessing Functionality Not Properly Constrained by ACLs |
|
| Likelyhood of attack |
Typical severity |
| High |
High |
|
| Summary |
In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to. |
| Prerequisites |
The application must be navigable in a manner that associates elements (subsections) of the application with ACLs. The various resources, or individual URLs, must be somehow discoverable by the attacker The administrator must have forgotten to associate an ACL or has associated an inappropriately permissive ACL with a particular navigable resource. |
| Execution Flow |
| Step |
Phase |
Description |
Techniques |
| 1 |
Explore |
[Survey] The attacker surveys the target application, possibly as a valid and authenticated user |
- Spidering web sites for all available links
- Brute force guessing of resource names
- Brute force guessing of user names / credentials
- Brute force guessing of function names / actions
|
| 2 |
Explore |
[Identify Functionality] At each step, the attacker notes the resource or functionality access mechanism invoked upon performing specific actions |
- Use the web inventory of all forms and inputs and apply attack data to those inputs.
- Use a packet sniffer to capture and record network traffic
- Execute the software in a debugger and record API calls into the operating system or important libraries. This might occur in an environment other than a production environment, in order to find weaknesses that can be exploited in a production environment.
|
| 3 |
Experiment |
[Iterate over access capabilities] Possibly as a valid user, the attacker then tries to access each of the noted access mechanisms directly in order to perform functions not constrained by the ACLs. |
- Fuzzing of API parameters (URL parameters, OS API parameters, protocol parameters)
|
|
| Solutions | In a more general setting, the administrator must mark every resource besides the ones supposed to be exposed to the user as accessible by a role impossible for the user to assume. The default security setting must be to deny access and then grant access only to those resources intended by business logic. |
| Related Weaknesses |
|
CWE ID
|
Description
|
| CWE-276 |
Incorrect Default Permissions |
| CWE-285 |
Improper Authorization |
| CWE-434 |
Unrestricted Upload of File with Dangerous Type |
| CWE-693 |
Protection Mechanism Failure |
| CWE-732 |
Incorrect Permission Assignment for Critical Resource |
| CWE-1193 |
Power-On of Untrusted Execution Core Before Enabling Fabric Access Control |
| CWE-1220 |
Insufficient Granularity of Access Control |
| CWE-1297 |
Unprotected Confidential Information on Device is Accessible by OSAT Vendors |
| CWE-1311 |
Improper Translation of Security Attributes by Fabric Bridge |
| CWE-1314 |
Missing Write Protection for Parametric Data Values |
| CWE-1315 |
Improper Setting of Bus Controlling Capability in Fabric End-point |
| CWE-1318 |
Missing Support for Security Features in On-chip Fabrics or Buses |
| CWE-1320 |
Improper Protection for Out of Bounds Signal Level Alerts |
| CWE-1321 |
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') |
| CWE-1327 |
Binding to an Unrestricted IP Address |
|
| Related CAPECS |
|
CAPEC ID
|
Description
|
| CAPEC-17 |
An attack of this type exploits a system's configuration that allows an adversary to either directly access an executable file, for example through shell access; or in a possible worst case allows an adversary to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface. |
| CAPEC-122 |
An adversary is able to exploit features of the target that should be reserved for privileged users or administrators but are exposed to use by lower or non-privileged accounts. Access to sensitive information and functionality must be controlled to ensure that only authorized users are able to access these resources. |
|
| Taxonomy: ATTACK |
|
Entry ID
|
Entry Name
|
| 1574.010 |
Hijack Execution Flow: ServicesFile Permissions Weakness |
|