Execution with Unnecessary Privileges
Draft Base
Structure: Simple
Description
This vulnerability occurs when software runs with higher permissions than it actually needs to perform its tasks. This excessive privilege creates security risks by opening doors to new attacks or making existing weaknesses more dangerous.
Think of it like giving a hotel guest a master key to the entire building when they only need access to their room. When applications or services run with elevated privileges (like root or SYSTEM), a simple bug or compromise can have catastrophic consequences. An attacker who exploits a flaw in this over-privileged component gains those same high-level permissions, allowing them to install malware, steal sensitive data, or disable security controls across the entire system. To prevent this, developers should follow the principle of least privilege (PoLP). This means explicitly configuring each component to run with the minimum permissions required for its specific function. In practice, this involves using service accounts with restricted rights, dropping privileges after initialization, and separating high-privilege tasks into isolated, minimal processes. Regular privilege audits are essential to ensure configurations don't drift over time toward excessive access.
Common Consequences 1
Scope: ConfidentialityIntegrityAvailabilityAccess Control
Impact: Gain Privileges or Assume IdentityExecute Unauthorized Code or CommandsRead Application DataDoS: 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. 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.
Detection Methods 10
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.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.
Automated Static Analysis - Binary or BytecodeHigh
According to SOAR [REF-1479], the following detection techniques may be useful:
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Highly cost effective:
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Compare binary / bytecode to application permission manifest
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Cost effective for partial coverage:
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Bytecode Weakness Analysis - including disassembler + source code weakness analysis
Binary Weakness Analysis - including disassembler + source code weakness analysisManual Static Analysis - Binary or BytecodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
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Cost effective for partial coverage:
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Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomaliesDynamic Analysis with Automated Results InterpretationSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Cost effective for partial coverage:
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Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteriaDynamic Analysis with Manual Results InterpretationSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
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Cost effective for partial coverage:
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Host Application Interface ScannerManual Static Analysis - Source CodeHigh
According to SOAR [REF-1479], the following detection techniques may be useful:
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Highly cost effective:
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Manual Source Code Review (not inspections)
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Cost effective for partial coverage:
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Focused Manual Spotcheck - Focused manual analysis of sourceAutomated Static Analysis - Source CodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
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Cost effective for partial coverage:
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Source code Weakness Analyzer
Context-configured Source Code Weakness AnalyzerAutomated Static AnalysisSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
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Cost effective for partial coverage:
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Configuration Checker
Permission Manifest AnalysisArchitecture or Design ReviewHigh
According to SOAR [REF-1479], the following detection techniques may be useful:
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Highly cost effective:
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Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Formal Methods / Correct-By-Construction
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Cost effective for partial coverage:
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Attack ModelingPotential Mitigations 7
Phase: Architecture and DesignOperation
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 Privilege Dropping / Lowering Errors. Avoid weaknesses such as Authentication Bypass Using an Alternate Path or Channel and Unprotected Alternate Channel 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 Privilege Dropping / Lowering Errors. Avoid weaknesses such as Authentication Bypass Using an Alternate Path or Channel and Unprotected Alternate Channel 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 Improper Check for Dropped Privileges. 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.
Phase: OperationSystem Configuration
Strategy: Environment Hardening
Ensure that the software runs properly under the United States Government Configuration Baseline (USGCB) [REF-199] or an equivalent hardening configuration guide, which many organizations use to limit the attack surface and potential risk of deployed software.
Demonstrative Examples 4
ID : DX-126
This code temporarily raises the program's privileges to allow creation of a new user folder.Code Example:
Bad
Python
python#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.
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.
Code Example:
Bad
C
cConstraining 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.
This application intends to use a user's location to determine the timezone the user is in:
Code Example:
Bad
Java
javaThis 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.
ID : DX-111
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:
Code Example:
Bad
XML
xmlDuring 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:
Code Example:
Bad
Java
javaWhile 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 9
CVE-2007-4217FTP 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-2008-1877Program runs with privileges and calls another program with the same privileges, which allows read of arbitrary files.
CVE-2007-5159OS incorrectly installs a program with setuid privileges, allowing users to gain privileges.
CVE-2008-4638Composite: application running with high privileges (Execution with Unnecessary Privileges) allows user to specify a restricted file to process, which generates a parsing error that leaks the contents of the file (Generation of Error Message Containing Sensitive Information).
CVE-2008-0162Program does not drop privileges before calling another program, allowing code execution.
CVE-2008-0368setuid root program allows creation of arbitrary files through command line argument.
CVE-2007-3931Installation script installs some programs as setuid when they shouldn't be.
CVE-2020-3812mail 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.
CVE-2003-0908Product launches Help functionality while running with raised privileges, allowing command execution using Windows message to access "open file" dialog.
References 8
Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors
Katrina Tsipenyuk, Brian Chess, and Gary McGraw
NIST Workshop on Software Security Assurance Tools Techniques and Metrics • NIST
07-11-2005
ID: REF-6
The Protection of Information in Computer Systems
Jerome H. Saltzer and Michael D. Schroeder
Proceedings of the IEEE 63
09-1975
ID: REF-196
Least Privilege
Sean Barnum and Michael Gegick
14-09-2005
ID: REF-76
Writing Secure Code
Michael Howard and David LeBlanc
Microsoft Press
04-12-2002
ID: REF-7
United States Government Configuration Baseline (USGCB)
NIST
ID: REF-199
24 Deadly Sins of Software Security
Michael Howard, David LeBlanc, and John Viega
McGraw-Hill
2010
ID: REF-44
The Art of Software Security Assessment
Mark Dowd, John McDonald, and Justin Schuh
Addison Wesley
2006
ID: REF-62
State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation
Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, and Rama S. Moorthy
07-2014
ID: REF-1479
Likelihood of Exploit
Medium
Applicable Platforms
Languages:
Not Language-Specific : Undetermined
Technologies:
Mobile : Undetermined
Modes of Introduction
Implementation
Installation
Architecture and Design
Operation
Related Weaknesses
Taxonomy Mapping
- 7 Pernicious Kingdoms
- The CERT Oracle Secure Coding Standard for Java (2011)
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
- ISA/IEC 62443
Notes
RelationshipThere is a close association with Improper Isolation or Compartmentalization (Insufficient Separation of Privileges). Improper Isolation or Compartmentalization is about providing separate components for each privilege; Execution with Unnecessary Privileges is about ensuring that each component has the least amount of privileges possible.
MaintenancePrivilege Dropping / Lowering Errors, Least Privilege Violation, and Execution with Unnecessary Privileges are all closely related and possibly overlapping. Privilege Dropping / Lowering Errors is probably better suited as a category. Both Least Privilege Violation and Execution with Unnecessary Privileges are in active use by the community. The "least privilege" phrase has multiple interpretations.
MaintenanceThe 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.
OtherPrivilege 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.
OtherSignal 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.