CVE-2023-27010: CWE-250: Execution with Unnecessary Privileges (4.10)

Weakness ID: 250

Abstraction: Base
Structure: Simple

Description

The product performs an operation at a privilege level that is higher than the minimum level required, which creates new weaknesses or amplifies the consequences of other weaknesses.

Extended Description

New weaknesses can be exposed because running with extra privileges, such as root or Administrator, can disable the normal security checks being performed by the operating system or surrounding environment. Other pre-existing weaknesses can turn into security vulnerabilities if they occur while operating at raised privileges.

Privilege management functions can behave in some less-than-obvious ways, and they have different quirks on different platforms. These inconsistencies are particularly pronounced if you are transitioning from one non-root user to another. Signal handlers and spawned processes run at the privilege of the owning process, so if a process is running as root when a signal fires or a sub-process is executed, the signal handler or sub-process will operate with root privileges.

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.

Relevant to the view “Research Concepts” (CWE-1000)

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 “Software Development” (CWE-699)

Nature

Type

ID

Name

MemberOf

Category - a CWE entry that contains a set of other entries that share a common characteristic.

265

Privilege Issues

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

MemberOf

Category - a CWE entry that contains a set of other entries that share a common characteristic.

1015

Limit Access

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

Implementation

REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Installation

Architecture and Design

If an application has this design problem, then it can be easier for the developer to make implementation-related errors such as CWE-271 (Privilege Dropping / Lowering Errors). In addition, the consequences of Privilege Chaining (CWE-268) can become more severe.

Operation

Applicable Platforms

This listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Class: Mobile (Undetermined Prevalence)

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

Confidentiality
Integrity
Availability
Access Control

Technical Impact: Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands; Read Application Data; DoS: Crash, Exit, or Restart

An attacker will be able to gain access to any resources that are allowed by the extra privileges. Common results include executing code, disabling services, and reading restricted data.

Likelihood Of Exploit

Demonstrative Examples

Example 1

This code temporarily raises the program’s privileges to allow creation of a new user folder.

(bad code)

Example Language: Python

def makeNewUserDir(username):

if invalidUsername(username):

#avoid CWE-22 and CWE-78
print(‘Usernames cannot contain invalid characters’)
return False

try:

raisePrivileges()
os.mkdir(‘/home/’ + username)
lowerPrivileges()

except OSError:

print(‘Unable to create new user directory for user:’ + username)
return False

return True

While the program only raises its privilege level to create the folder and immediately lowers it again, if the call to os.mkdir() throws an exception, the call to lowerPrivileges() will not occur. As a result, the program is indefinitely operating in a raised privilege state, possibly allowing further exploitation to occur.

Example 2

The following code calls chroot() to restrict the application to a subset of the filesystem below APP_HOME in order to prevent an attacker from using the program to gain unauthorized access to files located elsewhere. The code then opens a file specified by the user and processes the contents of the file.

(bad code)

Example Language: C

chroot(APP_HOME);
chdir(“/”);
FILE* data = fopen(argv[1], “r+”);
…

Constraining the process inside the application’s home directory before opening any files is a valuable security measure. However, the absence of a call to setuid() with some non-zero value means the application is continuing to operate with unnecessary root privileges. Any successful exploit carried out by an attacker against the application can now result in a privilege escalation attack because any malicious operations will be performed with the privileges of the superuser. If the application drops to the privilege level of a non-root user, the potential for damage is substantially reduced.

Example 3

This application intends to use a user’s location to determine the timezone the user is in:

(bad code)

Example Language: Java

locationClient = new LocationClient(this, this, this);
locationClient.connect();
Location userCurrLocation;
userCurrLocation = locationClient.getLastLocation();
setTimeZone(userCurrLocation);

This is unnecessary use of the location API, as this information is already available using the Android Time API. Always be sure there is not another way to obtain needed information before resorting to using the location API.

Example 4

This code uses location to determine the user’s current US State location.

First the application must declare that it requires the ACCESS_FINE_LOCATION permission in the application’s manifest.xml:

(bad code)

Example Language: XML

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

During execution, a call to getLastLocation() will return a location based on the application’s location permissions. In this case the application has permission for the most accurate location possible:

(bad code)

Example Language: Java

locationClient = new LocationClient(this, this, this);
locationClient.connect();
Location userCurrLocation;
userCurrLocation = locationClient.getLastLocation();
deriveStateFromCoords(userCurrLocation);

While the application needs this information, it does not need to use the ACCESS_FINE_LOCATION permission, as the ACCESS_COARSE_LOCATION permission will be sufficient to identify which US state the user is in.

Observed Examples

Reference

Description

CVE-2007-4217

FTP client program on a certain OS runs with setuid privileges and has a buffer overflow. Most clients do not need extra privileges, so an overflow is not a vulnerability for those clients.

CVE-2008-1877

Program runs with privileges and calls another program with the same privileges, which allows read of arbitrary files.

CVE-2007-5159

OS incorrectly installs a program with setuid privileges, allowing users to gain privileges.

CVE-2008-4638

Composite: application running with high privileges (CWE-250) allows user to specify a restricted file to process, which generates a parsing error that leaks the contents of the file (CWE-209).

CVE-2008-0162

Program does not drop privileges before calling another program, allowing code execution.

CVE-2008-0368

setuid root program allows creation of arbitrary files through command line argument.

CVE-2007-3931

Installation script installs some programs as setuid when they shouldn’t be.

CVE-2020-3812

mail program runs as root but does not drop its privileges before attempting to access a file. Attacker can use a symlink from their home directory to a directory only readable by root, then determine whether the file exists based on the response.

Potential Mitigations

Phases: Architecture and Design; Operation

Strategy: Environment Hardening

Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Phase: Architecture and Design

Strategy: Separation of Privilege

Identify the functionality that requires additional privileges, such as access to privileged operating system resources. Wrap and centralize this functionality if possible, and isolate the privileged code as much as possible from other code [REF-76]. Raise privileges as late as possible, and drop them as soon as possible to avoid CWE-271. Avoid weaknesses such as CWE-288 and CWE-420 by protecting all possible communication channels that could interact with the privileged code, such as a secondary socket that is only intended to be accessed by administrators.

Phase: Architecture and Design

Strategy: Attack Surface Reduction

Identify the functionality that requires additional privileges, such as access to privileged operating system resources. Wrap and centralize this functionality if possible, and isolate the privileged code as much as possible from other code [REF-76]. Raise privileges as late as possible, and drop them as soon as possible to avoid CWE-271. Avoid weaknesses such as CWE-288 and CWE-420 by protecting all possible communication channels that could interact with the privileged code, such as a secondary socket that is only intended to be accessed by administrators.

Phase: Implementation

Perform extensive input validation for any privileged code that must be exposed to the user and reject anything that does not fit your strict requirements.

Phase: Implementation

When dropping privileges, ensure that they have been dropped successfully to avoid CWE-273. As protection mechanisms in the environment get stronger, privilege-dropping calls may fail even if it seems like they would always succeed.

Phase: Implementation

If circumstances force you to run with extra privileges, then determine the minimum access level necessary. First identify the different permissions that the software and its users will need to perform their actions, such as file read and write permissions, network socket permissions, and so forth. Then explicitly allow those actions while denying all else [REF-76]. Perform extensive input validation and canonicalization to minimize the chances of introducing a separate vulnerability. This mitigation is much more prone to error than dropping the privileges in the first place.

Phases: Operation; System Configuration

Strategy: Environment Hardening

Ensure that the software runs properly under the Federal Desktop Core Configuration (FDCC) [REF-199] or an equivalent hardening configuration guide, which many organizations use to limit the attack surface and potential risk of deployed software.

Detection Methods

Manual Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Note: These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Black Box

Use monitoring tools that examine the software’s process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon, RegMon, Process Monitor, and other Sysinternals utilities (Windows); and sniffers and protocol analyzers that monitor network traffic.

Attach the monitor to the process and perform a login. Look for library functions and system calls that indicate when privileges are being raised or dropped. Look for accesses of resources that are restricted to normal users.

Note: Note that this technique is only useful for privilege issues related to system resources. It is not likely to detect application-level business rules that are related to privileges, such as if a blog system allows a user to delete a blog entry without first checking that the user has administrator privileges.

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:

• Compare binary / bytecode to application permission manifest

Cost effective for partial coverage:

• Bytecode Weakness Analysis - including disassembler + source code weakness analysis

• Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: High

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:

• Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:

• Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteria

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:

• Host Application Interface Scanner

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:

• Manual Source Code Review (not inspections)

Cost effective for partial coverage:

• Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:

• Source code Weakness Analyzer

• Context-configured Source Code Weakness Analyzer

Effectiveness: SOAR Partial

Automated Static Analysis

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:

• Configuration Checker

• Permission Manifest Analysis

Effectiveness: SOAR Partial

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:

• Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

• Formal Methods / Correct-By-Construction

Cost effective for partial coverage:

• Attack Modeling

Effectiveness: High

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.

Notes

Relationship

There is a close association with CWE-653 (Insufficient Separation of Privileges). CWE-653 is about providing separate components for each privilege; CWE-250 is about ensuring that each component has the least amount of privileges possible.

Maintenance

CWE-271, CWE-272, and CWE-250 are all closely related and possibly overlapping. CWE-271 is probably better suited as a category. Both CWE-272 and CWE-250 are in active use by the community. The “least privilege” phrase has multiple interpretations.

Maintenance

The Taxonomy_Mappings to ISA/IEC 62443 were added in CWE 4.10, but they are still under review and might change in future CWE versions. These draft mappings were performed by members of the “Mapping CWE to 62443” subgroup of the CWE-CAPEC ICS/OT Special Interest Group (SIG), and their work is incomplete as of CWE 4.10. The mappings are included to facilitate discussion and review by the broader ICS/OT community, and they are likely to change in future CWE versions.

Taxonomy Mappings

Mapped Taxonomy Name

Node ID

Fit

Mapped Node Name

7 Pernicious Kingdoms

Often Misused: Privilege Management

The CERT Oracle Secure Coding Standard for Java (2011)

SER09-J

Minimize privileges before deserializing from a privilege context

ISA/IEC 62443

Part 4-1

Req SD-4

ISA/IEC 62443

Part 4-2

Req 4.4

References

Content History

Submissions

Submission Date

Submitter

Organization

2006-07-19

7 Pernicious Kingdoms

Contributions

Contribution Date

Contributor

Organization

2023-01-24

“Mapping CWE to 62443” Sub-Working Group

CWE-CAPEC ICS/OT SIG

Suggested mappings to ISA/IEC 62443.

Modifications

Modification Date

Modifier

Organization

2008-09-08

CWE Content Team

MITRE

updated Description, Modes_of_Introduction, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings

2008-10-14

CWE Content Team

MITRE

updated Description, Maintenance_Notes

2009-01-12

CWE Content Team

MITRE

updated Common_Consequences, Description, Likelihood_of_Exploit, Maintenance_Notes, Name, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships, Time_of_Introduction

2009-03-10

CWE Content Team

MITRE

updated Potential_Mitigations

2009-05-27

CWE Content Team

MITRE

updated Related_Attack_Patterns

2010-02-16

CWE Content Team

MITRE

updated Detection_Factors, Potential_Mitigations, References

2010-06-21

CWE Content Team

MITRE

updated Detection_Factors, Potential_Mitigations

2011-03-29

CWE Content Team

MITRE

updated Relationships

2011-06-01

CWE Content Team

MITRE

updated Common_Consequences, Relationships, Taxonomy_Mappings

2011-06-27

CWE Content Team

MITRE

updated Demonstrative_Examples, Relationships

2011-09-13

CWE Content Team

MITRE

updated Potential_Mitigations, References, Relationships

2012-05-11

CWE Content Team

MITRE

updated References, Related_Attack_Patterns, Relationships

2012-10-30

CWE Content Team

MITRE

updated Potential_Mitigations

2013-07-17

CWE Content Team

MITRE

updated Applicable_Platforms

2014-02-18

CWE Content Team

MITRE

updated Demonstrative_Examples

2014-07-30

CWE Content Team

MITRE

updated Detection_Factors

2017-11-08

CWE Content Team

MITRE

updated Modes_of_Introduction, References, Relationships

2018-03-27

CWE Content Team

MITRE

updated References

2019-01-03

CWE Content Team

MITRE

updated Taxonomy_Mappings

2019-09-19

CWE Content Team

MITRE

updated Demonstrative_Examples

2020-02-24

CWE Content Team

MITRE

updated Applicable_Platforms, Detection_Factors, Observed_Examples, References, Relationships, Type

2022-04-28

CWE Content Team

MITRE

updated Observed_Examples

2022-10-13

CWE Content Team

MITRE

updated References

2023-01-31

CWE Content Team

MITRE

updated Description, Maintenance_Notes, Taxonomy_Mappings

Previous Entry Names

Change Date

Previous Entry Name

2008-01-30

Often Misused: Privilege Management

2009-01-12

Design Principle Violation: Failure to Use Least Privilege

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