Chrome’s safety staff tirelessly works to ensure a secure browsing experience. We invest in safeguards to render exploitable vulnerabilities impossible, deploy mitigations that increase the difficulty of leveraging a detected safety issue, and engage in controlled testing environments (sandboxing) to minimize the impact of remote safety situations. When identifying potential targets for speculation, it’s crucial to consider how threat actors typically identify and capitalize on weaknesses.
In this post, we examine several key axes used to assess the potential harm to customers resulting from exploits, as well as how these criteria apply specifically to the Google Chrome browser.
Traditionally, the Google Chrome Safety Staff has made significant investments and driven efforts to create a safer online environment. We pioneered the development of browsers and revolutionized the way people interact with information on the internet. Currently, we are investing in strengthening our existing C++ codebase by implementing security measures to prevent vulnerabilities, while also enhancing detection capabilities through improved Under-Allocated-Free (UAF) detection techniques. Concerns about user harm and assault underscore the importance of our vulnerability reporting and payouts for bugs discovered through our. Within a prolonged timeframe, the Chrome Safety Team advocates for implementing system upgrades such as lightweight process limitations, reduced privileges for GPU and NPU containers, enhanced software isolation mechanisms, and support for hardware-based isolation techniques that enforce memory security and traffic management.
When evaluating a proposed safety adjustment, it’s easy to succumb to the temptation of safety nihilism. While it’s tempting to dismiss alterations that merely complicate exploitation without eliminating it entirely, a more nuanced approach is warranted, as even slight obstructions can hinder its feasibility. Despite the scales we’re operating on, incremental improvements remain valuable endeavors. As users increasingly rely on Chrome and its chromium-based counterparts, the cumulative effect of these improvements exacts a tangible toll on malicious actors.
Risk Mannequin for Code Execution
Our primary goal for ensuring online safety is to empower users with the confidence to explore new websites and navigate through links without fear of compromise. This document prioritizes strategies for preventing code execution stemming from vulnerabilities and exploits, but its principles can be applied to mitigate various security threats altogether?
Malicious actors typically seek to achieve a specific objective, which they can accomplish by exploiting vulnerabilities outside of Chrome’s secure and isolated processing environments. Attackers seek out information or capabilities that we do not intentionally make available to websites or extensions operating within the sandboxed rendering environment. This could potentially execute malicious code, allowing users or systems with elevated privileges to scrutinize the memory of other processes, access sensitive credentials, and open local files. Here is the rewritten text:
In this tutorial, we focus on attackers that initiate with JavaScript or possess the capability to send packets to Chrome, ultimately yielding a valuable outcome. While we focus on limiting dialogue, we prioritize memory-safety points as the highlight of our ongoing hardening initiatives.
Chrome Safety can effectively curtail risks to users by limiting attackers’ scope for maneuvering. Defenses that render certain attackers’ ultimate goals unachievable or significantly more challenging possess inherent value. Users of Google’s Chrome browser face numerous challenges. While cautioning against fixating on isolated adversaries or individuals, it’s crucial to recognize that even seemingly innocuous actors can pose significant threats when leveraging the internet. Chrome safeguards users against an array of threats from diverse attackers and hazards. Ignoring the dimensional frameworks that govern Chrome’s interactions with specific attackers or vectors, a singular focus can be detrimental to comprehensive security strategies. By reducing threats or increasing costs for just a portion of potential risks, someone, somewhere can become safer while using the internet.
While acknowledging the existence of more significant vulnerabilities, it is crucial to consistently acknowledge and prioritise initiatives that effectively mitigate or modestly reduce the availability or effectiveness of the most critical bugs and escalation pathways.
Good Bugs and Unhealthy Bugs
While all bugs pose a threat, certain vulnerabilities are more susceptible to being exploited. Excessive worth bugs in software components and ineffective escalation mechanisms for attackers often possess one or more of the following characteristics:
Dependable
A vulnerability that consistently causes a system crash or allows immediate exploitation on launch has limited usefulness compared to one that can be reliably triggered through various means at any time. Crashes may lead to detection by the goalkeeper or defenders who converge on the resulting accumulation of crashed players. Attackers may not always have multiple opportunities to launch their attacks. Bugs that exclusively occur when running entirely separate threads typically demand specific sequence requirements, thus necessitating additional resource allocation or processing time to resolve. Since malicious actors may attempt to exploit vulnerabilities by inducing a browser crash and then reinitiate attacks, Chrome’s multi-process architecture for handling cross-domain iframe interactions can inadvertently facilitate such attempts. Bugs that exclusively manifest upon the primary browser process’s shutdown prove more challenging for attackers to exploit, as they’re granted only one opportunity per session.
Low-interaction
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Our baseline for minimal interaction assumes users access websites through Chrome to click on hyperlinks, leveraging the browser’s functionality as a starting point. Attacks that rely on a specific action or movement from the victim, whether anticipated or not, pose a heightened risk to the attacker. The likelihood of exploiting this bug decreases as it requires prolonged residence on the system, whereas the exploit’s yield also diminishes due to unpredictable motion patterns and increased suspicion among users who exhibit unfamiliar behavior.
Ubiquitous
A bug with a broad reach across multiple platforms, exploitable through identical means each time, will prove more valuable than its single-platform counterpart that requires separate exploitation and porting efforts. Exploits targeting specific hardware configurations or less common platforms are most effective when attackers have a clear understanding of their victims’ systems. The fewer bugs an attacker must combine in order to craft a successful exploit means the lower the required maintenance and testing investment, ultimately leading to more streamlined attacks. While Chrome’s issues may exclusively appear on Linux, other problems persist across all our platforms. While Google Chrome is undoubtedly one of the most widely used software products currently, some of its dependencies are significantly more prevalent, making it prudent for attackers to focus efforts on identifying and exploiting vulnerabilities in third-party libraries that Chrome relies upon. Bugs that necessitate manual intervention via extensions or rely on specific hardware configurations are far less valuable than those that can be accessed and resolved from any internet-connected webpage at ease?
Quick
Strategies that demand considerable setup or execution time are significantly less likely to succeed and more susceptible to being detected. The increased complexity of crafting reliable exploits from gradually emerging bugs prolongs the compile-test-debug process, posing significant challenges.
Scriptable
Vulnerabilities that necessitate an exploit to facilitate grooming or state manipulation for successful exploitation become even more valuable when their environment can be programmatically controlled, allowing for targeted and repeatable attacks. As you get closer to the code where the bug resides, managing the context in which it’s triggered becomes increasingly straightforward. Exploiting bugs hidden within complex codecs or unmanaged threads used by an unsuspecting victim can prove challenging for attackers seeking to automate their malicious scripts. Scriptable bugs are seamlessly integrated into an exploit chain, whereas non-scriptable bugs may only be useful when combined with a related vulnerability. Vulnerabilities adjacent to a scripting engine like JavaScript are more easily exploitable, thereby amplifying the severity of bugs in third-party libraries that exhibit different behavior in Chrome compared to other environments? Finesse issues in tightly coupled APIs like WebGPU are effortlessly scriptable. Chrome extensions can manipulate the browser’s internal state and user interface, enabling scripting of various user interactions, such as opening, closing, and rearranging tabs.
Straightforward to Check
To maintain long-term exploit credibility, attackers must ensure their techniques remain effective across varying versions of Chrome and its underlying operating systems. Bugs that can be consistently reproduced in a controlled environment can be easily examined and diagnosed. Bugs that arise exclusively through human interaction, following complex community conferences, or necessitating collaboration with external partners are particularly challenging to reproduce and diagnose. To replicate this issue, users seek a sophisticated simulation of their environment or an updated variant of Google Chrome that accurately mimics their surroundings, thereby inducing the flaw. Maintaining a system of this complexity requires substantial resources, rendering minor flaws relatively unexciting. Does the description of a scriptable word relate to its environmental context? Scriptable environments facilitate streamlined testing approaches.
Silent
Silent bugs that quietly manipulate system state without raising alarms or triggering noticeable events are far more concerning than those that produce visible symptoms, such as alerts, emissions, or repetitive network traffic. Unwanted side effects embody metrics, crashes or slowdowns, pop ups & prompts, system logs and artifacts like downloaded information. While unwanted side effects may not directly impact the primary objective of an attack, they could inadvertently lead to the discovery of targeted tactics at a later time. A previously unknown vulnerability may still be identifiable without the attacker’s sensitive information, despite initial appearances suggesting otherwise?
Lengthy-lived
Attackers seek vulnerabilities that are difficult to identify and fix. Analyzing and integrating a bug into an exploitation suite requires careful upfront work, as attackers seek vulnerabilities that can remain exploitable for an extended period. Attackers often market exploits as subscription-based services, which could see their revenue model severely impacted if they were to identify bugs at an earlier rate. Newly released products or those uncovered through widely adopted fuzzing techniques are more likely to be quickly identified and addressed.
Focused
Attackers will endeavour to conceal their exploitation techniques by shielding vulnerabilities and seeking out bugs that can only be triggered when they are confident in being exploitable by specific, targeted individuals or groups? With relative ease, one can identify an online individual by leveraging cookies, communal information, and the features of the online platform. Disrupting entrenched supply chain networks and eliminating inefficiencies through innovative logistics solutions. No unencrypted internet traffic should make it more difficult to concentrate on each vulnerability.
Straightforward to escalate
Modern web browsers employ various countermeasures that render it more challenging to exploit certain vulnerabilities or exploit chains. Attackers typically leverage primitives provided by a vulnerability and manage them to achieve a specific objective, such as executing arbitrary system commands. While some bugs may not seamlessly transition into a subsequent phase, they could potentially require significant integration efforts or specialized tools to enable progression to the next stage. The utility of certain bugs lies in their ability to seamlessly integrate with subsequent escalation or lateral motion processes. While individual bugs may not be inherently useful on their own, they can become valuable when combined with other bugs to create a reliable or practical outcome. Several pieces of confidential data align with this category. A secure read-where primitive or strategy to identify allocated memory makes arbitrary writes easier to execute. When a particular escalation method frequently appears in exploit chains or examples, it’s crucial to investigate whether it can be mitigated.
Straightforward to seek out
While initially unexpected, a glaring bug that’s easily identifiable can still prove valuable until Chrome rectifies the issue and potential exploiters pivot. As Chrome’s source code is publicly accessible, attackers can swiftly locate newly published security or stability patches and potentially exploit vulnerabilities until updates are deployed, leaving users vulnerable for an extended period. While fuzz testing effectively detects superficial issues, it often falls short in uncovering more sophisticated problems that require specific input scenarios, which can still be identified through targeted exploration. An attacker might opt to focus on identifying vulnerabilities within a specific realm that typically lacks robust security scrutiny. Lastingly, attackers might deliberately introduce bugs into libraries, thereby launching a supply-chain attack.
Troublesome to seek out
The difficulty lies in identifying certain bugs, which may be easily exploitable by an attacker due to their design, or challenging to find because they exist in an under-explored area of the codebase, or are concealed behind complex logic that’s hard to test through fuzzing. As the bug is identified early on, its longevity increases, making it a valuable asset for multiple stakeholders who are less likely to detect it. Attackers seeking to reverse-engineer and exploit closed-source components within Google’s Chrome browser may gain access to vulnerabilities that a wider security community might not detect, thus creating an elevated risk for users.
Some attackers operate with an enterprise model, while others rely on a budget. In general, we worry about cybercriminals seeking financial gain, as well as hackers intent on surveilling private citizens. When carefully tailored to their unique dynamics, bugs and escalation mechanisms prove valuable assets for groups, fostering collaboration and resolving issues efficiently. We can explore various mitigation strategies tailored to distinct attackers’ diverse financial profiles. A novice thespian targeting unrefined clientele might employ an overly simplistic and ineffective marketing strategy, characterized by a limited reach and minimal impact. Are you looking for ways to boost your cybersecurity defenses and protect against harmful attacks? They simply need to succeed in a minuscule proportion of instances. Teams could also explore the opportunity to develop restricted bug discovery approaches, whereas alternatively, they could leverage short-lived, already-fixed bugs and integrate them into exploit kits. While some adversaries might theoretically possess unlimited financial resources, they would likely still opt for the most economical and reliable means to achieve their goals. The deprecation of Flash and its subsequent replacement by exploiting v8 perhaps best exemplifies this phenomenon?
While deploying mitigations or eradicating attack surfaces, we are ultimately striving to impede adversaries’ ability to achieve their goals. Attackers may alter their tactics if the economic incentives behind their exploits are altered by reducing the payoff from exploiting vulnerabilities that facilitate their malicious activities. Some actors might proactively invest significant resources in maintaining a focus area to cater to users engaging with our online presence, leaving us to hypothesize about their potential reactions to the changes we implement? Addressing the root causes of subtle attacks requires a holistic approach, involving comprehensive removal of vulnerability vectors and escalation pathways.
Profits from exploits typically take the form of linear chains, comprising sequential steps that commence with identifying a vulnerability, progress through various escalation phases, and culminate in achieving the attacker’s immediate objective of either executing code or gaining unauthorized access outside the sandboxed rendering process. Through our Vulnerability Rewards Programme, we solicit reports of such vulnerabilities. A JavaScript kind confusion enables an out-of-bounds learn/write operation within the V8 sandbox, which can be exploited as a V8 sandbox escape bug allowing learn/write operations within the renderer; further, overwriting a JIT write/execute area permits arbitrary code execution, ultimately resulting in calls to system or browser APIs that facilitate a full browser sandbox escape. The initial attack vector allows for the successful exploitation of the target’s browser, ultimately culminating in unmitigated code execution, likely paving the way for more sinister motives. Effective strategies for multi-layered protection often focus on identifying specific vulnerabilities that, when exploited, trigger a security breach.
The terrain introduced to the universe of attackers is a complex web of untapped opportunities, both familiar to some and hidden from view, waiting to be uncovered. The notion that a defensive measure can prove successful, albeit imperfect, is often misunderstood by attackers who assume that every possible individual must be reached and exploited.
Tempting though it may seem to dismiss a mitigation or removal of an assault floor solely because attackers could potentially find alternative means to achieve their goals, a more nuanced approach is warranted. Despite this mindset’s subtlety, it likely assumes the most adept attackers and their most coveted objectives. The breadth of our existing research corpus requires expansion. Many attackers face significant limitations in their abilities and capabilities. Some individuals were able to attach N-day modules onto crimson group instruments. While some contributors may have a well-oiled pipeline exploiting a specific aspect of Chrome’s vast codebase with impressive results, they often require guidance and additional resources to identify valuable bugs if their current niche were to be disrupted. Exploit kits are often promoted by those who seek to eliminate escalation mechanisms. As beforehand dependable exploits became more dated, they might potentially become less reliable, taking longer to yield desired results. Enhancing security measures in Google Chrome strengthens protection for users, rendering attacks more challenging to execute.
While acknowledging the importance of implementing mitigations that don’t “hand over” escalation paths, it’s crucial to prioritize measures that effectively prevent or significantly hinder exploitation of initial vulnerabilities, thereby rendering a substantial portion of mitigation strategies ineffective. While reported assaults often stem from initial vulnerabilities, it’s unwise to focus solely on addressing those early weaknesses, as doing so overlooks crucial interventions that can occur throughout the entire assault cycle. Rise in attacker utility leads directly to a decrease in attacker prices and an increase in market risk.
A mechanism capable of mitigating or reducing bugs in Chrome offers tangible benefits for select users along one or more dimensions of utility.
