Intel Chips Lazy FP Vulnerability Could Leak Secure Data

A group of security researchers have found a new vulnerability with Intels chips that can theoretically allow an attack to utilize the Lazy FP state of the process and gain access to sensitive data.

Intel is warning that the Spectre and Meltdown variant 3A exploit will allow a program to obtain scraps of the Floating Point Unit (FPU) context of another app on Intel Core and Xeon processors.
The tracking number for this is
CVE-2018-3665
.
This moderate security problem happens because system software can utilize what is called the Lazy FP state restore technique to delay the restoring of state until an instruction operating on that state is actually executed by the new process. This may allow a local process to infer data utilizing Lazy FP state restore from another process through a speculative execution side channel.
Intel recommends system software developers utilize the Eager FP state restore in lieu of Lazy FP state restore. This includes:
Modern Linux: Going from kernel version 4.9, which was released in 2016
Windows: Including Windows Server 2016
Other Kernels: Including OpenSD and DragonflyBSD, which already use this technique routinely
(Source:
Flickr
)
Windows Server 2008 will need a patch, and the Linux kernel team is said to be back-porting mitigations to pre-4.9 kernels.
These techniques do not carry a performance hit. It has been found that eager state switching can even increase performance.
This kind of vulnerability -- though there are no known exploits in the wild at this time --could compromise cryptographic keys that are used to secure data in the system. Crypto programs routinely utilize the FPU to carry out the mathematical operations needed for cryptography.
Other external programs, such as malware, might be able to obtain or guess parts of these cryptographic keys by examining the state of the FPU.
Intel credited Julian Stecklina from Amazon Germany; Thomas Prescher from Cyberus Technology GmbH; Zdenek Sojka from SYSGO AG; as well as researcher Colin Perceiver, for bringing this latest side-channel vulnerability to light.
It has also been reported that Google found that its systems are secured against the lazy FPU state restore.
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Red Hat Linux also addressed
the problem. The open source company notes, RHEL-7 will automatically default to (safe) eager floating point register restore on Sandy Bridge and newer Intel processors. AMD processors are not affected.
The company also say that users can mitigate this issue on older processors in RHEL 7 by booting the kernel with the eagerfpu=on parameter to enable eager FPU restore mode.
RHEL 6 and earlier versions are affected by the problem, but Red Hat says it will be releasing updates that will fix it.
Its also been reported by the Register
that the announcement of the vulnerability was supposed to occur on June 27, but the BSD teams issued an early mitigation fix after Intel declined to work with them under embargo. This forced Intel to go public earlier than it had planned.
Related posts:
Spectre Number 4 Disclosure Raises Fresh Hardware Alarms
Throwhammer & Nethhammer Show How Chips Are Vulnerable to Bit Flips
Spectre NG Flaws Reportedly Found in Intel Chips
In Wake of Spectre & Meltdown, Intel Shifts Memory Scanning to GPU
— Larry Loeb has written for many of the last centurys major dead tree computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

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Intel Chips Lazy FP Vulnerability Could Leak Secure Data