> August 2019 — During our initial disclosure, the Wi-Fi Alliance privately created security recommendations to mitigate our attacks. In these recommendations, they claim that Brainpool curves are safe to use, at least if products securely implement Dragonfly’s quadratic residue test (i.e. it must be implemented without side-channel leaks). However, we found that using Brainpool curves introduces a second class of side-channel leaks in the Dragonfly handshake of WPA3. In other words, even if the advice of the Wi-Fi Alliance is followed, implementations remain at risk of attacks. This demonstrates that implementing Dragonfly and WPA3 without side-channel leaks is surprisingly hard. It also, once again, shows that privately creating security recommendations and standards is at best irresponsible and at worst inept.

That last line.

source: solar

> RSA is an intrinsically fragile cryptosystem containing countless foot-guns which the average software engineer cannot be expected to avoid. Weak parameters can be difficult, if not impossible, to check, and its poor performance compels developers to take risky shortcuts. Even worse, padding oracle attacks remain rampant 20 years after they were discovered. While it may be theoretically possible to implement RSA correctly, decades of devastating attacks have proven that such a feat may be unachievable in practice.

source: L

> It is important to build up a systematic understanding of these attacks and possible defenses

source: grugq

> RAMBleed is based on a previous side channel called Rowhammer, which enables an attacker to flip bits in the memory space of other processes. We show in our paper that an attacker, by observing Rowhammer-induced bit flips in her own memory, can deduce the values in nearby DRAM rows. Thus, RAMBleed shifts Rowhammer from being a threat not only to integrity, but confidentiality as well. Furthermore, unlike Rowhammer, RAMBleed does not require persistent bit flips, and is thus effective against ECC memory commonly used by server computers.

source: HN

We now need meta sites to link to the attack sites.

https://zombieloadattack.com/

https://mdsattacks.com/

https://software.intel.com/security-software-guidance/insights/deep-dive-intel-analysis-microarchitectural-data-sampling

> A side-channel attack can extract private keys from certain versions of Qualcomm’s secure keystore. Recent Android devices include a hardware-backed keystore, which developers can use to protect their cryptographic keys with secure hardware. On some devices, Qualcomm’s TrustZone-based keystore leaks sensitive information through the branch predictor and memory caches, enabling recovery of 224 and 256-bit ECDSA keys. We demonstrate this by extracting an ECDSA P-256 private key from the hardware-backed keystore on the Nexus 5X.

Paper: https://www.nccgroup.trust/globalassets/our-research/us/whitepapers/2019/hardwarebackedhesit.pdf

source: HN

> In theory, it would be sufficient to defeat either of the two components of an attack. Since we do not know of any way to defeat any of the parts perfectly, we designed and deployed mitigations that greatly reduce the amount of information that is leaked into CPU caches and mitigations that make it hard to recover the hidden state.

> Fortunately or unfortunately, our offensive research advanced much faster than our defensive research, and we quickly discovered that software mitigation of all possible leaks due to Spectre was infeasible. This was due to a variety of reasons. First, the engineering effort diverted to combating Spectre was disproportionate to its threat level. In V8 we face many other security threats that are much worse, from direct out-of-bound reads due to regular bugs (faster and more direct than Spectre), out-of-bound writes (impossible with Spectre, and worse) and potential remote code execution (impossible with Spectre and much, much worse). Second, the increasingly complicated mitigations that we designed and implemented carried significant complexity, which is technical debt and might actually increase the attack surface, and performance overheads. Third, testing and maintaining mitigations for microarchitectural leaks is even trickier than designing gadgets themselves, since it’s hard to be sure the mitigations continue working as designed. At least once, important mitigations were effectively undone by later compiler optimizations. Fourth, we found that effective mitigation of some variants of Spectre, particularly variant 4, to be simply infeasible in software, even after a heroic effort by our partners at Apple to combat the problem in their JIT compiler.

source: L

> One of the main advantages of WPA3 is that, thanks to its underlying Dragonfly handshake, it’s near impossible to crack the password of a network. Unfortunately, we found that even with WPA3, an attacker within range of a victim can still recover the password of the network. This allows the adversary to steal sensitive information such as credit cards, password, emails, and so on, when the victim uses no extra layer of protection such as HTTPS. Fortunately, we expect that our work and coordination with the Wi-Fi Alliance will allow vendors to mitigate our attacks before WPA3 becomes widespread.

> As you might have heard, we recently got our paper on padding oracle attacks accepted to the USENIX Security Conference. In this paper, we describe and evaluate a scanning methodology with which we found several padding oracle vulnerabilities in devices from various vendors. In total, we found that 1.83% of the Alexa Top 1 Million have padding oracle vulnerabilities.

source: green

> Well-known DOM APIs

Only a few dozen issues.

source: grugq

> This article is a detailed explanation of how I could have exploited Google’s Monorail issue tracker to leak sensitive information (vulnerable source code files and line numbers) from private bug reports through a XS-Search attack.

> We introduce SMoTherSpectre, a speculative code-reuse attack that leverages port-contention in simultaneously multi-threaded processors (SMoTher) as a side channel to leak information from a victim process. SMoTher is a fine-grained side channel that detects contention based on a single victim instruction. To discover real-world gadgets, we describe a methodology and build a tool that locates SMoTher-gadgets in popular libraries. In an evaluation on glibc, we found more than hundred gadgets that can be used to leak some information. Finally, we demonstrate a proof-of-concept attack against encryption using the OpenSSL library, leaking information about the plaintext through gadgets in libcrypto and glibc.

Also: https://nebelwelt.net/blog/20190306-SMoTherSpectre.html

Also: https://github.com/HexHive/SMoTherSpectre

> Modern microarchitectures incorporate optimization techniques such as speculative loads and store forwarding to improve the memory bottleneck. The processor executes the load speculatively before the stores, and forwards the data of a preceding store to the load if there is a potential dependency. This enhances performance since the load does not have to wait for preceding stores to complete. However, the dependency prediction relies on partial address information, which may lead to false dependencies and stall hazards.

In this work, we are the first to show that the dependency resolution logic that serves the speculative load can be exploited to gain information about the physical page mappings. Microarchitectural side-channel attacks such as Rowhammer and cache attacks rely on the reverse engineering of the virtual-to-physical address mapping. We propose the SPOILER attack which exploits this leakage to speed up this reverse engineering by a factor of 256. Then, we show how this can improve the Prime+Probe attack by a 4096 factor speed up of the eviction set search, even from sandboxed environments like JavaScript. Finally, we improve the Rowhammer attack by showing how SPOILER helps to conduct DRAM row conflicts deterministically with up to 100% chance, and by demonstrating a double-sided Rowhammer attack with normal user’s privilege. The later is due to the possibility of detecting contiguous memory pages using the SPOILER leakage.

When worlds collide.

source: L

> The recent discovery of the Spectre and Meltdown attacks represents a watershed moment not just for the field of Computer Security, but also of Programming Languages. This paper explores speculative side-channel attacks and their implications for programming languages. These attacks leak information through micro-architectural side-channels which we show are not mere bugs, but in fact lie at the foundation of optimization. We identify three open problems, (1) finding side-channels, (2) understanding speculative vulnerabilities, and (3) mitigating them. For (1) we introduce a mathematical meta-model that clarifies the source of side-channels in simulations and CPUs. For (2) we introduce an architectural model with speculative semantics to study recently-discovered vulnerabilities. For (3) we explore and evaluate software mitigations and prove one correct for this model. Our analysis is informed by extensive offensive research and defensive implementation work for V8, the production JavaScript virtual machine in Chrome. Straightforward extensions to model real hardware suggest these vulnerabilities present formidable challenges for effective, efficient mitigation. As a result of our work, we now believe that speculative vulnerabilities on today’s hardware defeat all language-enforced confidentiality with no known comprehensive software mitigations, as we have discovered that untrusted code can construct a universal read gadget to read all memory in the same address space through side-channels. In the face of this reality, we have shifted the security model of the Chrome web browser and V8 to process isolation.

> You weep over the side channel attacks and you curse Intel. You have the luxury of not knowing what I know; that speculative execution, while dangerous, probably saves cores. And my optimizations, while grotesque and incomprehensible to you, save cores. You don’t want in order execution because deep down in places you don’t talk about at parties, you want the most instructions per cycle.

> We present a new hardware-agnostic side-channel attack that targets one of the most fundamental software caches in modern computer systems: the operating system page cache. The page cache is a pure software cache that contains all disk-backed pages, including program binaries, shared libraries, and other files, and our attacks thus work across cores and CPUs. Our side-channel permits unprivileged monitoring of some memory accesses of other processes, with a spatial resolution of 4KB and a temporal resolution of 2 microseconds on Linux (restricted to 6.7 measurements per second) and 466 nanoseconds on Windows (restricted to 223 measurements per second); this is roughly the same order of magnitude as the current state-of-the-art cache attacks. We systematically analyze our side channel by demonstrating different local attacks, including a sandbox bypassing high-speed covert channel, timed user-interface redressing attacks, and an attack recovering automatically generated temporary passwords. We further show that we can trade off the side channel’s hardware agnostic property for remote exploitability. We demonstrate this via a low profile remote covert channel that uses this page-cache side-channel to exfiltrate information from a malicious sender process through innocuous server requests. Finally, we propose mitigations for some of our attacks, which have been acknowledged by operating system vendors and slated for future security patches.

source: L

> Over the last twenty years researchers and implementors had spent a huge amount of effort in developing and deploying numerous mitigation techniques which were supposed to plug all the possible sources of Bleichenbacher-like leakages. However, as we show in this paper most implementations are still vulnerable to several novel types of attack based on leakage from various microarchitectural side channels: Out of nine popular implementations of TLS that we tested, we were able to break the security of seven implementations with practical proof-of-concept attacks. We demonstrate the feasibility of using those Cache-like ATacks (CATs) to perform a downgrade attack against any TLS connection to a vulnerable server, using a BEAST-like Man in the Browser attack.

source: green

> Website fingerprinting attacks, which use statistical analysis on network traffic to compromise user privacy, have been shown to be effective even if the traffic is sent over anonymity-preserving networks such as Tor. The classical attack model used to evaluate website fingerprinting attacks assumes an on-path adversary, who can observe all traffic traveling between the user’s computer and the Tor network. In this work we investigate these attacks under a different attack model, inwhich the adversary is capable of running a small amount of unprivileged code on the target user’s computer. Under this model, the attacker can mount cache side-channel attacks, which exploit the effects of contention on the CPU’s cache, to identify the website being browsed. In an important special case of this attack model, a JavaScript attack is launched when the target user visits a website controlled by the attacker. The effectiveness of this attack scenario has never been systematically analyzed,especially in the open-world model which assumes that the user is visiting a mix of both sensitive and non-sensitive sites. In this work we show that cache website fingerprinting attacks in JavaScript are highly feasible, even when they are run from highly restrictive environments, such as the Tor Browser .Specifically, we use machine learning techniques to classify traces of cache activity. Unlike prior works, which try to identify cache conflicts, our work measures the overall occupancy of the last-level cache. We show that our approach achieves high classification accuracy in both the open-world and the closed-world models. We further show that our techniques are resilient both to network-based defenses and to side-channel countermeasures introduced to modern browsers as a response to the Spectre attack.

source: green

> Where many people thought that high-end servers were safe from the (unpatchable) Rowhammer bitflip vulnerability in memory chips, new research from VUSec, the security group at Vrije Universiteit Amsterdam, shows that this is not the case. Since prominent security researchers and companies have suggested that ECC provides pretty good protection [1,2,3], and exploitable bitflips on ECC memory are seen by many as the “unholy grail” for Rowhammer attacks, the new attack to reliably flip bits that completely bypass ECC protection is a major step forward in Rowhammer research.

> To answer the research question above, we first needed to fully understand how ECC is implemented. Unfortunately, this is not trivial. In general, CPU manufacturers omit details of ECC implementation. In addition, the closed nature of hardware makes our task even more difficult. Thus, we first reverse engineered several ECC implementations and showed their guarantees. This part of the work was pretty crazy and involved freezing memory chips and transplanting them (“cold boot attack”), sticking syringe needles into the sockets of memory modules to inject errors, and many other techniques besides. Long story short, after a year of probing and analyzing, we finally understood how ECC memory worked in detail.

source: solar

> Despite these mitigations, this work presents a novel side-channel attack against ECDSA and DSA. The attack targets a common implementation pattern that is found in many cryptographic libraries. In fact, about half of the libraries that were tested exhibited the vulnerable pattern. This pattern is exploited in a full proof of concept attack against OpenSSL, demonstrating that it is possible to extract a 256-bit ECDSA private key using a simple cache attack after observing only a few thousand signatures. The target of this attack is a previously unexplored part of (EC)DSA signature generation, which explains why mitigations are lacking and the issue is so widespread.

source: green