Microsoft SQL Elevation of Privilege Vulnerability
CVE-2021-1636
Security Vulnerability
Released: Jan 12, 2021
- Assigning CNA
- Microsoft
- CVE.org link
- CVE-2021-1636
- Impact
- Elevation of Privilege
- Max Severity
- Important
- CVSS Source
- Microsoft
- Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
- Metrics
- CVSS:3.1 8.8 / 7.7Base score metrics: 8.8 / Temporal score metrics: 7.7
Metric
Value
Base score metrics(8)
Attack Vector
This metric reflects the context by which vulnerability exploitation is possible. The Base Score increases the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable component.
Network
The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity
This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Such conditions may require the collection of more information about the target or computational exceptions. The assessment of this metric excludes any requirements for user interaction in order to exploit the vulnerability. If a specific configuration is required for an attack to succeed, the Base metrics should be scored assuming the vulnerable component is in that configuration.
Low
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required
This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.
Low
The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction
This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise the vulnerable component. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
None
The vulnerable system can be exploited without any interaction from any user.
Scope
Does a successful attack impact a component other than the vulnerable component? If so, the Base Score increases and the Confidentiality, Integrity and Authentication metrics should be scored relative to the impacted component.
Unchanged
An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality
This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
High
There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity
This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.
High
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability
This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. It refers to the loss of availability of the impacted component itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of an impacted component.
High
There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Temporal score metrics(3)
Exploit Code Maturity
This metric measures the likelihood of the vulnerability being attacked, and is typically based on the current state of exploit techniques, public availability of exploit code, or active, 'in-the-wild' exploitation.
Unproven
No publicly available exploit code is available, or an exploit is theoretical.
Remediation Level
The Remediation Level of a vulnerability is an important factor for prioritization. The typical vulnerability is unpatched when initially published. Workarounds or hotfixes may offer interim remediation until an official patch or upgrade is issued. Each of these respective stages adjusts the temporal score downwards, reflecting the decreasing urgency as remediation becomes final.
Official Fix
A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.
Report Confidence
This metric measures the degree of confidence in the existence of the vulnerability and the credibility of the known technical details. Sometimes only the existence of vulnerabilities are publicized, but without specific details. For example, an impact may be recognized as undesirable, but the root cause may not be known. The vulnerability may later be corroborated by research which suggests where the vulnerability may lie, though the research may not be certain. Finally, a vulnerability may be confirmed through acknowledgement by the author or vendor of the affected technology. The urgency of a vulnerability is higher when a vulnerability is known to exist with certainty. This metric also suggests the level of technical knowledge available to would-be attackers.
Confirmed
Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability.
Please see Common Vulnerability Scoring System for more information on the definition of these metrics.
Exploitability
The following table provides an exploitability assessment for this vulnerability at the time of original publication.
- Publicly disclosed
- No
- Exploited
- No
- Exploitability assessment
- Exploitation Less Likely
FAQ
How can an attacker exploit this vulnerability?
An authenticated attacker can send data over a network to an affected SQL Server when configured to run an Extended Event session.
There are GDR and/or CU (Cumulative Update) updates offered for my version of SQL Server. How do I know which update to use?
- First, determine your SQL Server version number. For more information on determining your SQL Server version number, see Microsoft Knowledge Base Article 321185 - How to determine the version, edition, and update level of SQL Server and its components.
- Second, in the table below, locate your version number or the version range that your version number falls within. The corresponding update is the one you need to install.
Note If your SQL Server version number is not represented in the table below, your SQL Server version is no longer supported. Please upgrade to the latest Service Pack or SQL Server product in order to apply this and future security updates.
| Update number | Title | Apply if current product version is… | This security update also includes servicing releases up through… |
|---|---|---|---|
| 4583458 | Security update for SQL Server 2019 RTM GDR: Jan 12, 2021 | 15.0.2000.5 - 15.0.2070.41 | KB 4517790 - Previous SQL19 RTM GDR |
| 4583459 | Security update for SQL Server 2019 RTM CU8: Jan 12, 2021 | 15.0.4003.23 - 15.0.4073.23 | KB 4577194 – SQL19 RTM CU8 |
| 4583456 | Security update for SQL Server 2017 RTM GDR: Jan 12, 2021 | 14.0.1000.169 - 14.0.2027.2 | KB4505224 - Previous SQL17 RTM GDR |
| 4583457 | Security update for SQL Server 2017 RTM CU22: Jan 12, 2021 | 14.0.3006.16 - 14.0.3356.20 | KB4577467 – SQL17 RTM CU22 |
| 4583460 | Security update for SQL Server 2016 Service Pack 2 (GDR): Jan 12, 2021 | 13.0.5026.0 - 13.0.5102.14 | KB4532097 - Previous SQL16 SP2 GDR |
| 4583461 | Security update for SQL Server 2016 Service Pack 2 CU15: Jan 12, 2021 | 13.0.5149.0 - 13.0.5850.14 | KB4577775 – SQL16 SP2 CU15 |
| 4583463 | Security update for SQL Server 2014 Service Pack 3 (GDR): Jan 12, 2021 | 12.0.6024.0 - 12.0.6118.4 | KB4532095 - Previous SQL14 SP3 GDR |
| 4583462 | Security update for SQL Server 2014 Service Pack 2 CU4: Jan 12, 2021 | 12.0.6205.1 - 12.0.6372.1 | KB4535288 – SQL14 SP3 CU4 |
| 4583465 | Security update for SQL Server 2012 Service Pack 4 (QFE): Jan 12, 2021 | 11.0.7001.0 - 11.0.7493.4 | KB4532098 – Previous SQL12 SP4 QFE |
What are the GDR and CU update designations and how do they differ?
The General Distribution Release (GDR) and Cumulative Update (CU) designations correspond to the two different servicing options in place for SQL Server baseline releases. A baseline can be either an RTM release or a Service Pack release.
- GDR updates – cumulatively only contain security updates for the given baseline.
- CU updates – cumulatively contain all functional fixes and security updates for the given baseline.
For any given baseline, either the GDR or CU updates could be options (see below).
- If SQL Server installation is at a baseline version, you can choose either the GDR or CU update.
- If SQL Server installation has intentionally only installed past GDR updates, then choose to install the GDR update package.
- If SQL Server installation has intentionally installed previous CU updates, then chose to install the CU security update package.
Note: You are allowed to make a change from GDR updates to CU updates ONE TIME. Once a SQL Server CU update is applied to a SQL Server installation, there is NO way to go back to the GDR update path.
Can the security updates be applied to SQL Server instances on Windows Azure (IaaS)?
Yes. SQL Server instances on Windows Azure (IaaS) can be offered the security updates through Microsoft Update, or customers can download the security updates from Microsoft Download Center and apply them manually.
Acknowledgements
Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information.
Security Updates
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle.
Release date Descending
Product
Platform
Impact
Max Severity
Article
Download
Build Number
Jan 12, 2021
Microsoft SQL Server 2019 for x64-based Systems (GDR)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2019 for x64-based Systems (CU 8)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2016 Service Pack 2 for x64-based Systems (CU 15)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2017 for x64-based Systems (CU 22)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2014 Service Pack 3 for x64-based Systems (CU 4)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2014 Service Pack 3 for 32-bit Systems (CU 4)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2014 Service Pack 3 for 32-bit Systems (GDR)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2016 for x64-based Systems Service Pack 2 (GDR)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2014 Service Pack 3 for x64-based Systems (GDR)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2017 for x64-based Systems (GDR)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2012 for x64-based Systems Service Pack 4 (QFE)
-
Elevation of Privilege
Important
- -
Jan 12, 2021
Microsoft SQL Server 2012 for 32-bit Systems Service Pack 4 (QFE)
-
Elevation of Privilege
Important
- -
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Disclaimer
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Revisions
version
revisionDate
description
1.0
Jan 12, 2021
Information published.
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