Researchers have discovered yet another speculative execution vulnerability that can allow attackers to steal potentially sensitive information from devices with Intel processors.
The flaw, identified by researchers at Bitdefender, is similar to Spectre Variant 1, which researchers disclosed in January 2018. However, unlike in the case of the original Spectre, for which Intel released processor microcode patches, the new vulnerability has been addressed only with software updates.
The newly disclosed side-channel attack method, dubbed SWAPGS Attack, is related to how Intel processors handle the SWAPGS instruction during speculative execution, a performance optimization technique that involves executing instructions before they are actually needed.
A skilled attacker who has already compromised the targeted system could use a SWAPGS attack to gain access to data stored in the memory that they would normally not be allowed to access. They could use this to escalate privileges or obtain sensitive information, such as passwords and encryption keys.
According to Bitdefender, the vulnerability impacts millions of home and enterprise devices that use Intel CPUs supporting SWAPGS and WRGSBASE instructions. This includes a vast majority of CPUs made since 2012. The cybersecurity firm has published a whitepaper detailing its findings, along with a video showing an attack against a machine running Windows 10.
After consultations with industry partners, Intel decided that the best mitigation for this flaw, tracked as CVE-2019-1125, would be at the software layer. Microsoft released a software update that should address the issue in July and published an advisory on August 6 to coincide with Bitdefender’s disclosure. Previous mitigations for Spectre attacks do not provide protection for SWAPGS attacks.
“To exploit this vulnerability, an attacker would have to log on to an affected system and run a specially crafted application. The vulnerability would not allow an attacker to elevate user rights directly, but it could be used to obtain information that could be used to try to compromise the affected system further,” Microsoft said.
Red Hat has published a knowledgebase article describing the impact of the vulnerability on Linux systems, and informed users that updates to the Linux kernel are required.
Devices with AMD processors do not appear to be vulnerable to the SWAPGS attack.
“Based on external and internal analysis, AMD believes it is not vulnerable to the SWAPGS variant attacks because AMD products are designed not to speculate on the new GS value following a speculative SWAPGS. For the attack that is not a SWAPGS variant, the mitigation is to implement our existing recommendations for Spectre variant 1,” AMD said.
News of the SWAPGS vulnerability comes just weeks after the disclosure of several Microarchitectural Data Sampling (MDS) vulnerabilities affecting most Intel processors made in the last decade.
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