libreoffice openoffice bug allows hackers spoof

LIBREOFFICE OPENOFFICE BUG ALLOWS HACKERS SPOOF GENERATOR
LIBREOFFICE OPENOFFICE BUG ALLOWS HACKERS SPOOF PATCH

The DRBG is then seeded early in the boot process from a combination of Program can continuously read /dev/random to consume all of the That eliminates a kind of denial-of-service attack where a user-space the one that feeds /dev/random), though, his patchĬreates a new kernel_pool that is only accessible to the kernel

LIBREOFFICE OPENOFFICE BUG ALLOWS HACKERS SPOOF PATCH

He used that code as theīasis for this new patch set. Inclusion of his CPU jitter RNG in October 2013. To seed the kernel's DRBG so that it complied. Since the worst case for get_random_bytes() is that itĬompletely deterministic, Xu felt that some other mechanism should be used Was compliant with the US National Institute of Standards and TechnologyĭRBGs that specifies seeding DRBGs from non-deterministic sources.

In mid-April, kernel crypto subsystem maintainer Herbert Xu asked Müller whether the current DRBG for someĮmbedded devices or virtual machines), that pool will not have been seededįrom enough events to provide the entropy required.

LIBREOFFICE OPENOFFICE BUG ALLOWS HACKERS SPOOF GENERATOR

Kernel's deterministic random bit generator (DRBG) is currently initializedīy making a call to get_random_bytes(), which uses the Repeatedly calls jent_gen_entropy() to fill theīuffer with the requested amount of random data.Īdding the CPU jitter RNG is only part of what the patch set does, however. Jent_read_entropy(), which takes a buffer and length and Getting larger amounts of random data is done with The jent_gen_entropy() function generates aĦ4-bit random number by calling jent_measure_jitter() 64 times. This function implies that careful retesting must be done. Is used to measure the CPU execution time jitter. Thisįunction not only acts as folding operation, but this function's execution Is the root cause why the code shall be compiled without optimization. Jent_fold_time() function explains a bit further: In fact, there is a test in the code that will cause the build to fail if optimization is enabled to avoid the possibility of getting bad random numbers from a misconfigured build. In order to preserve those measurements, optimization for the jitter random number Part of what is being measured for jitter in the execution time. There are faster ways to do the folding operation, but his algorithm is

Inefficient' calculation to fold the value down to a single bit. It then gets a timestamp and calculates a delta from the previous Unpredictable wait states into the measurement. Is larger than the L1 cache of the processor, which should introduce some It loops through and simply adds one to the value stored there (whichĬauses both a load and a store). The jitter entropy module allocates a 2KB buffer during initialization that The first step is to introduce some noise into the measurement based on It returns a single bit that has been calculated based on the jitter It is effectively a ' random bit generator', since Gathering lives in the jent_measure_jitter()įunction. The heart of the algorithm to implement Müller's jitter measurement Processors show enough jitter (in a statistical sense) to be used as an As Müller's paper shows, a wide variety of today's Management, frequency scaling, and so on can all contribute to changing theĮxecution time. States, instruction and data caches, branch prediction, interrupts, power The fill level of the instruction pipelines, memory wait

There are numerous CPU-level activities that lead to unpredictability inĮxecution time. Hardware-level access to the CPU cannot predict this jitter, which makes itĪ good source of entropy, according to Müller's lengthy paper on Measures that execution time precisely multiple times, it will show On a modern processor, there are many different factors that can impact theĪmount of time it takes to execute the same set of instructions. Source that is always present: CPU execution time jitter. Müller seeks to remedy that by using entropy that is collected from a Interrupts that may not be present yet-or at all. Sources of entropy depend on events like the timing of user input or disk Availability of entropy, especially for embedded devices early in theĬommonly discussed problem in the kernel random number community.

Libreoffice openoffice bug allows hackers spoof