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attackerkbAttackerKBAKB:2034EF9D-C938-410E-8DB8-9CDEB9C41A7A
HistoryJul 14, 2021 - 12:00 a.m.

CVE-2021-31979

2021-07-1400:00:00
attackerkb.com
30

7.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

7.2 High

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

0.0004 Low

EPSS

Percentile

7.9%

Windows Kernel Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-33771, CVE-2021-34514.

Recent assessments:

gwillcox-r7 at July 14, 2021 5:35pm UTC reported:

Update: Looks like this was used by the exploit brokerage company Candiru along with CVE-2021-33771 to deliver spyware to targeted users, which according to Microsoft’s blog post, affected at least 100 victims in Palestine, Israel, Iran, Lebanon, Yemen, Spain, United Kingdom, Turkey, Armenia, and Singapore. Victims include human rights defenders, dissidents, journalists, activists, and politicians.

Hmm, this is a particularly juicy bug as it seems to affect all Windows systems from Windows 7 up to the latest Windows 10. This is in contrast to CVE-2021-33771, which only affects Windows 8.1 and later. Both bugs affect the Windows Kernel and are being actively exploited in the wild for LPE.

There is little information on what actually is the issue here, although <https://twitter.com/mavillon1/status/1415149124064878593/&gt; suggests that MiFlashDataSecton, EtwpUpdatePeriodicCaptureState and AlpcpProcessSynchronousRequest may be possible culprits and reviewing AlpcpProcessSynchronousRequest shows that a potential integer overflow was fixed.

Given that Microsoft also lists the attack complexity for both vulnerabilities as Low it seems likely that other researchers will find a way to replicate these vulnerabilities and create working PoCs for them, particularly given that they have been exploited in the wild. Based on this evidence, it is highly recommended to patch these issues as soon as possible.

Further updates will be made to this post if and when these CVEs are tied to specific vulnerable functions.

Assessed Attacker Value: 4
Assessed Attacker Value: 4Assessed Attacker Value: 3

7.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

7.2 High

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

0.0004 Low

EPSS

Percentile

7.9%