cbcvebase.
CVE-2018-3639
published 2018-05-22

CVE-2018-3639: Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are…

PriorityP188medium5.5CVSS 3.1
AVLACLPRLUINSUCHINAN
ITWEXPLOITVulnCheck KEVRansomwareInitial access
Exploited in the wild
EPSS
60.63%
99.0th percentile
Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are known may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis, aka Speculative Store Bypass (SSB), Variant 4.

Affected

435 ranges· showing 25
VendorProductVersion rangeFixed in
applemacos_mojave
applemacos_mojave_10.14.1_security_update_2018-002_high_sierra_security_update_2018-0
armcortex-a
armcortex-a
armcortex-a
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
debiandebian_linux
debiandebian_linux
debianintel-microcode< intel-microcode 3.20180703.1 (bookworm)intel-microcode 3.20180703.1 (bookworm)
debianlinux< intel-microcode 3.20180703.1 (bookworm)intel-microcode 3.20180703.1 (bookworm)
debianxen< intel-microcode 3.20180703.1 (bookworm)intel-microcode 3.20180703.1 (bookworm)
intelatom_c
intelatom_c
intelatom_c
intelatom_c
intelatom_c
intelatom_c
intelatom_c
intelatom_c
intelatom_c
intelatom_c

Detection & IOCsextracted from sources · hover to see the quote

commandecho 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
  • CVE-2018-3639 (Spectre Variant 4 / Speculative Store Bypass) is most likely exploited via JavaScript JIT in web browsers; monitor for unusual JavaScript execution that generates native code performing speculative memory reads.
  • The PoC exploit uses a flush+reload cache side-channel technique (clflush + timing measurement) to leak data; detection can focus on high-frequency use of CLFLUSH instructions or anomalous cache-timing patterns in user-space processes.
  • Affected processors confirmed in PoC include Intel Skylake (i7-6600U), Intel Haswell (Xeon E5-1650 v3), and AMD PRO A8-9600; prioritize microcode/BIOS updates for these microarchitectures.
  • The most likely real-world attack vector for CVE-2018-3639 is via JavaScript in web browsers; browser-based mitigations (timer precision reduction, JIT hardening) deployed for Variant 1 also apply here.
  • ·Intel's microcode mitigation for Variant 4 is set to OFF by default; administrators must explicitly enable it, accepting a 2–8% performance impact.
  • ·Mitigations deployed for Spectre Variant 1 (January 2018) also provide coverage for Variant 4 (CVE-2018-3639) and are already available; ensure these are not disabled.
  • ·Red Hat included the ability to selectively disable Spectre/Meltdown patches; operators should verify these are not disabled on sensitive workloads.

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
nvdv2.02.1LOWAV:L/AC:L/Au:N/C:P/I:N/A:N
osv8.8HIGH
vulncheck5.5MEDIUM
vendor_ubuntu8.8HIGH
vendor_cisco5.5MEDIUM
vendor_debian5.5MEDIUM
vendor_oracle5.5MEDIUM
vendor_redhat5.5MEDIUM
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