CWE-639: Authorization Bypass Through User-Controlled KeyWeakness ID: 639 Vulnerability Mapping:
ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. |
Description The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. Extended Description Retrieval of a user record occurs in the system based on some key value that is under user control. The key would typically identify a user-related record stored in the system and would be used to lookup that record for presentation to the user. It is likely that an attacker would have to be an authenticated user in the system. However, the authorization process would not properly check the data access operation to ensure that the authenticated user performing the operation has sufficient entitlements to perform the requested data access, hence bypassing any other authorization checks present in the system. For example, attackers can look at places where user specific data is retrieved (e.g. search screens) and determine whether the key for the item being looked up is controllable externally. The key may be a hidden field in the HTML form field, might be passed as a URL parameter or as an unencrypted cookie variable, then in each of these cases it will be possible to tamper with the key value. One manifestation of this weakness is when a system uses sequential or otherwise easily-guessable session IDs that would allow one user to easily switch to another user's session and read/modify their data. Alternate Terms
Insecure Direct Object Reference / IDOR: | The "Insecure Direct Object Reference" term, as described in the OWASP Top Ten, is broader than this CWE because it also covers path traversal ( CWE-22). Within the context of vulnerability theory, there is a similarity between the OWASP concept and CWE-706: Use of Incorrectly-Resolved Name or Reference. |
Broken Object Level Authorization / BOLA: | BOLA is used in the 2019 OWASP API Security Top 10 and is said to be the same as IDOR. |
Horizontal Authorization: | "Horizontal Authorization" is used to describe situations in which two users have the same privilege level, but must be prevented from accessing each other's resources. This is fairly common when using key-based access to resources in a multi-user context. |
Common Consequences This table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.Scope | Impact | Likelihood |
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Access Control
| Technical Impact: Bypass Protection Mechanism Access control checks for specific user data or functionality can be bypassed. | | Access Control
| Technical Impact: Gain Privileges or Assume Identity Horizontal escalation of privilege is possible (one user can view/modify information of another user). | | Access Control
| Technical Impact: Gain Privileges or Assume Identity Vertical escalation of privilege is possible if the user-controlled key is actually a flag that indicates administrator status, allowing the attacker to gain administrative access. | |
Potential Mitigations
Phase: Architecture and Design For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested. |
Phases: Architecture and Design; Implementation Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected. |
Phase: Architecture and Design Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering. |
Relationships This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf 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 the user may want to explore.This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf 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 the user may want to explore.This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf 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 the user may want to explore. Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003) Nature | Type | ID | Name |
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ChildOf | Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. | 863 | Incorrect Authorization |
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf 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 the user may want to explore. Relevant to the view "Architectural Concepts" (CWE-1008) Nature | Type | ID | Name |
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MemberOf | Category - a CWE entry that contains a set of other entries that share a common characteristic. | 1011 | Authorize Actors |
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf 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 the user may want to explore. Relevant to the view "CISQ Data Protection Measures" (CWE-1340) Nature | Type | ID | Name |
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ChildOf | Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things. | 284 | Improper Access Control |
Modes Of Introduction The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.Phase | Note |
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Architecture and Design | REALIZATION: This weakness is caused during implementation of an architectural security tactic. |
Likelihood Of Exploit Demonstrative Examples Example 1 The following code uses a parameterized statement, which escapes metacharacters and prevents SQL injection vulnerabilities, to construct and execute a SQL query that searches for an invoice matching the specified identifier [1]. The identifier is selected from a list of all invoices associated with the current authenticated user. (bad code) Example Language: C#
...
conn = new SqlConnection(_ConnectionString);
conn.Open();
int16 id = System.Convert.ToInt16(invoiceID.Text);
SqlCommand query = new SqlCommand( "SELECT * FROM invoices WHERE id = @id", conn);
query.Parameters.AddWithValue("@id", id);
SqlDataReader objReader = objCommand.ExecuteReader();
...
The problem is that the developer has not considered all of the possible values of id. Although the interface generates a list of invoice identifiers that belong to the current user, an attacker can bypass this interface to request any desired invoice. Because the code in this example does not check to ensure that the user has permission to access the requested invoice, it will display any invoice, even if it does not belong to the current user. Observed Examples Reference | Description |
| An educational application does not appropriately restrict file IDs to a particular user. The attacker can brute-force guess IDs, indicating IDOR. |
Detection Methods
Automated Static Analysis Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) |
Memberships This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources. Vulnerability Mapping Notes Usage: ALLOWED (this CWE ID could be used to map to real-world vulnerabilities) | Reason: Acceptable-Use | Rationale: This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities. | Comments: Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction. |
Content History Submissions |
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Submission Date | Submitter | Organization |
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2008-01-30 (CWE Draft 8, 2008-01-30) | Evgeny Lebanidze | Cigital | | Modifications |
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Modification Date | Modifier | Organization |
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2008-09-08 | CWE Content Team | MITRE | updated Common_Consequences, Relationships, Type | 2008-10-14 | CWE Content Team | MITRE | updated Description | 2009-03-10 | CWE Content Team | MITRE | updated Relationships | 2009-05-27 | CWE Content Team | MITRE | updated Relationships | 2009-10-29 | CWE Content Team | MITRE | updated Common_Consequences | 2010-06-21 | CWE Content Team | MITRE | updated Relationships | 2011-03-29 | CWE Content Team | MITRE | updated Alternate_Terms, Applicable_Platforms, Description, Name, Potential_Mitigations, Relationships | 2011-06-01 | CWE Content Team | MITRE | updated Common_Consequences, Relationships | 2012-05-11 | CWE Content Team | MITRE | updated Relationships | 2013-02-21 | CWE Content Team | MITRE | updated Alternate_Terms, Common_Consequences | 2013-07-17 | CWE Content Team | MITRE | updated Relationships | 2014-07-30 | CWE Content Team | MITRE | updated Relationships | 2017-11-08 | CWE Content Team | MITRE | updated Description, Enabling_Factors_for_Exploitation, Modes_of_Introduction, Relationships | 2018-03-27 | CWE Content Team | MITRE | updated Relationships | 2019-06-20 | CWE Content Team | MITRE | updated Relationships | 2020-02-24 | CWE Content Team | MITRE | updated Relationships | 2020-06-25 | CWE Content Team | MITRE | updated Alternate_Terms | 2020-12-10 | CWE Content Team | MITRE | updated Relationships | 2021-03-15 | CWE Content Team | MITRE | updated Alternate_Terms | 2021-10-28 | CWE Content Team | MITRE | updated Relationships | 2023-04-27 | CWE Content Team | MITRE | updated Detection_Factors, Relationships | 2023-06-29 | CWE Content Team | MITRE | updated Mapping_Notes | 2023-10-26 | CWE Content Team | MITRE | updated Observed_Examples | 2024-02-29 (CWE 4.14, 2024-02-29) | CWE Content Team | MITRE | updated Demonstrative_Examples | Previous Entry Names |
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Change Date | Previous Entry Name |
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2011-03-29 | Access Control Bypass Through User-Controlled Key | |
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