Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Opis

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc.

A race condition violates these properties, which are closely related:

- Exclusivity - the code sequence is given exclusive access to the shared resource, i.e., no other code sequence can modify properties of the shared resource before the original sequence has completed execution.

- Atomicity - the code sequence is behaviorally atomic, i.e., no other thread or process can concurrently execute the same sequence of instructions (or a subset) against the same resource.

A race condition exists when an "interfering code sequence" can still access the shared resource, violating exclusivity.

The interfering code sequence could be "trusted" or "untrusted." A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

Inne nazwy

Race Condition

Skutki

• Availability

  DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)

  When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion.

• Availability

  DoS: Crash, Exit, or Restart; DoS: Instability

  When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.

• Confidentiality, Integrity

  Read Files or Directories; Read Application Data

  When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).

• Access Control

  Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; Bypass Protection Mechanism

  This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.

Zapobieganie

• Architecture and Design

  In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.

• Architecture and Design

  Use thread-safe capabilities such as the data access abstraction in Spring.

• Architecture and Design

  Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.

  Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

• Implementation

  When using multithreading and operating on shared variables, only use thread-safe functions.

• Implementation

  Use atomic operations on shared variables. Be wary of innocent-looking constructs such as "x++". This may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read, followed by a computation, followed by a write.

• Implementation

  Use a mutex if available, but be sure to avoid related weaknesses such as CWE-412.

• Implementation

  Avoid double-checked locking (CWE-609) and other implementation errors that arise when trying to avoid the overhead of synchronization.

• Implementation

  Disable interrupts or signals over critical parts of the code, but also make sure that the code does not go into a large or infinite loop.

• Implementation

  Use the volatile type modifier for critical variables to avoid unexpected compiler optimization or reordering. This does not necessarily solve the synchronization problem, but it can help.

• Architecture and Design, Operation · 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.

Przykłady podatności

• CVE-2024-38106 OS kernel stores sensitive data in improperly locked memory, allowing local users to gain privileges by winning a race condition
• CVE-2022-29527 Go application for cloud management creates a world-writable sudoers file that allows local attackers to inject sudo rules and escalate privileges to root by winning a race condition.
• CVE-2021-1782 Chain: improper locking (CWE-667) leads to race condition (CWE-362), as exploited in the wild per CISA KEV.
• CVE-2021-0920 Chain: mobile platform race condition (CWE-362) leading to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
• CVE-2020-6819 Chain: race condition (CWE-362) leads to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
• CVE-2019-18827 chain: JTAG interface is not disabled (CWE-1191) during ROM code execution, introducing a race condition (CWE-362) to extract encryption keys
• CVE-2019-1161 Chain: race condition (CWE-362) in anti-malware product allows deletion of files by creating a junction (CWE-1386) and using hard links during the time window in which a temporary file is created and deleted.
• CVE-2015-1743 TOCTOU in sandbox process allows installation of untrusted browser add-ons by replacing a file after it has been verified, but before it is executed
• CVE-2014-8273 Chain: chipset has a race condition (CWE-362) between when an interrupt handler detects an attempt to write-enable the BIOS (in violation of the lock bit), and when the handler resets the write-enable bit back to 0, allowing attackers to issue BIOS writes during the timing window [REF-1237].
• CVE-2008-5044 Race condition leading to a crash by calling a hook removal procedure while other activities are occurring at the same time.
• CVE-2008-2958 chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
• CVE-2008-1570 chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
• CVE-2008-0058 Unsynchronized caching operation enables a race condition that causes messages to be sent to a deallocated object.
• CVE-2008-0379 Race condition during initialization triggers a buffer overflow.
• CVE-2007-6599 Daemon crash by quickly performing operations and undoing them, which eventually leads to an operation that does not acquire a lock.
• CVE-2007-6180 chain: race condition triggers NULL pointer dereference
• CVE-2007-5794 Race condition in library function could cause data to be sent to the wrong process.
• CVE-2007-3970 Race condition in file parser leads to heap corruption.
• CVE-2008-5021 chain: race condition allows attacker to access an object while it is still being initialized, causing software to access uninitialized memory.
• CVE-2009-4895 chain: race condition for an argument value, possibly resulting in NULL dereference
• CVE-2009-3547 Chain: race condition (CWE-362) might allow resource to be released before operating on it, leading to NULL dereference (CWE-476)
• CVE-2006-5051 Chain: Signal handler contains too much functionality (CWE-828), introducing a race condition (CWE-362) that leads to a double free (CWE-415).

Słabość nadrzędna

• CWE-662 Improper Synchronization

Może prowadzić do

• CWE-416 Use After Free
• CWE-476 NULL Pointer Dereference

Słabości podrzędne

• CWE-364 Signal Handler Race Condition
• CWE-366 Race Condition within a Thread
• CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
• CWE-368 Context Switching Race Condition
• CWE-421 Race Condition During Access to Alternate Channel
• CWE-689 Permission Race Condition During Resource Copy
• CWE-1223 Race Condition for Write-Once Attributes
• CWE-1298 Hardware Logic Contains Race Conditions

Kiedy powstaje

• Architecture and Design
• Implementation — Programmers may assume that certain code sequences execute too quickly to be affected by an interfering code sequence; when they are not, this violates atomicity. For example, the single "x++" statement may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read (the original value of x), followed by a computation (x+1), followed by a write (save the result to x).

Dotyczy

C, C++, Java, Mobile, ICS/OT

Uwagi

The relationship between race conditions and synchronization problems (CWE-662) needs to be further developed. They are not necessarily two perspectives of the same core concept, since synchronization is only one technique for avoiding race conditions, and synchronization can be used for other purposes besides race condition prevention.

Race conditions in web applications are under-studied and probably under-reported. However, in 2008 there has been growing interest in this area.

Much of the focus of race condition research has been in Time-of-check Time-of-use (TOCTOU) variants (CWE-367), but many race conditions are related to synchronization problems that do not necessarily require a time-of-check.

From a classification/taxonomy perspective, the relationships between concurrency and program state need closer investigation and may be useful in organizing related issues.

Źródła

1. 24 Deadly Sins of Software Security — Michael Howard, David LeBlanc, John Viega, "Sin 13: Race Conditions." Page 205, McGraw-Hill, 2010
2. volatile - Multithreaded Programmer's Best Friend — Andrei Alexandrescu, Dr. Dobb's, 2008
3. Thread-safe webapps using Spring — Steven Devijver
4. Prevent race conditions — David Wheeler, 2007
5. Race Conditions, Files, and Security Flaws; or the Tortoise and the Hare Redux — Matt Bishop, 1995
6. Secure Programming for Linux and Unix HOWTO — David Wheeler, 2003
7. Discovering and Exploiting Named Pipe Security Flaws for Fun and Profit — Blake Watts, 2002
8. On Race Vulnerabilities in Web Applications — Roberto Paleari, Davide Marrone, Danilo Bruschi, Mattia Monga
9. Avoiding Race Conditions and Insecure File Operations — Apple Developer Connection
10. Top 25 Series - Rank 25 - Race Conditions — Johannes Ullrich, SANS Software Security Institute, 2010
11. Least Privilege — Sean Barnum, Michael Gegick, 2005
12. Intel BIOS locking mechanism contains race condition that enables write protection bypass — CERT Coordination Center, 2015
13. State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation — Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, Rama S. Moorthy, 2014