CVE-2019-18988
TeamViewer Desktop through 14.7.1965 allows a bypass of remote-login access control because the same key is used for different customers' installations.
High
Known exploited
- Severity
- 7.0 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 4.71%
- Chance of exploitation in the next 30 days. Higher than 91.81% of scored vulnerabilities.
- Known exploited
- Yes
- In CISA's catalog since Nov 3, 2021
- Fix
- None yet
- No fixed version published
Exploited in the wild. TeamViewer Desktop Bypass Remote Login Vulnerability (TeamViewer Desktop). Required action: Apply updates per vendor instructions. Due for U.S. federal agencies by May 3, 2022.
Description
TeamViewer Desktop through 14.7.1965 allows a bypass of remote-login access control because the same key is used for different customers' installations. It used a shared AES key for all installations since at least as far back as v7.0.43148, and used it for at least OptionsPasswordAES in the current version of the product. If an attacker were to know this key, they could decrypt protect information stored in the registry or configuration files of TeamViewer. With versions before v9.x , this allowed for attackers to decrypt the Unattended Access password to the system (which allows for remote login to the system as well as headless file browsing). The latest version still uses the same key for OptionPasswordAES but appears to have changed how the Unattended Access password is stored. While in most cases an attacker requires an existing session on a system, if the registry/configuration keys were stored off of the machine (such as in a file share or online), an attacker could then decrypt the required password to login to the system.
How to fix
No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.
Severity breakdown
CVSS 3.1 7.0
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Local
- Attack complexity
- High
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-521: Weak Password Requirements
The product does not require that users should have strong passwords.
How to prevent it
- Architecture and Design: A product's design should require adherance to an appropriate password policy. Specific password requirements depend strongly on contextual factors, but it is recommended to contain the following attributes: Enforcement of a minimum and maximum length Restrictions against password reuse Restrictions against using common passwords Restrictions against using contextual string in the password (e.g., user id, app name) Depending on the threat model, the password policy may include several additional attributes. Complex passwords requiring mixed character sets (alpha, numeric, special, mixed case) Increasing the range of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication. Unfortunately, a complex password may be difficult to memorize, encouraging a user to select a short password or to incorrectly manage the password (write it down). Another disadvantage of this approach is that it often does not result in a significant increases in overal password complexity due to people's predictable usage of various symbols. Large Minimum Length (encouraging passphrases instead of passwords) Increasing the number of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication. A disadvantage of this approach is that selecting a good passphrase is not easy and poor passwords can still be generated. Some prompting may be needed to encourage long un-predictable passwords. Randomly Chosen Secrets Generating a password for the user can help make sure that length and complexity requirements are met, and can result in secure passwords being used. A disadvantage of this approach is that the resulting password or passpharse may be too difficult to memorize, encouraging them to be written down. See NIST 800-63B [REF-1053] for further information on password requirements.
- Architecture and Design: Consider a second authentication factor beyond the password, which prevents the password from being a single point of failure. See CWE-308 for further information.
- Implementation: Consider implementing a password complexity meter to inform users when a chosen password meets the required attributes.
- Implementation: Previously, "password expiration" was widely advocated as a defense-in-depth approach to minimize the risk of weak passwords, and it has become a common practice. Password expiration requires a password to be changed within a fixed time window (such as every 90 days). However, this approach has significant limitations in the current threat landscape, and its utility has been reduced in light of the adoption of related protection mechanisms (such as password complexity and computational effort), along with the recognition that regular password changes often caused users to generate more predictable passwords. As a result, this is now a Discouraged Common Practice [REF-1488] [REF-1489], especially as the sole factor in protecting passwords. It is still strongly encouraged to force password changes in case of evidence of compromise, but this is not the same as a forced "expiration" on an arbitrary time frame.
CWE-521: Weak Password Requirements
The product does not require that users should have strong passwords.
How to prevent it
- Architecture and Design: A product's design should require adherance to an appropriate password policy. Specific password requirements depend strongly on contextual factors, but it is recommended to contain the following attributes: Enforcement of a minimum and maximum length Restrictions against password reuse Restrictions against using common passwords Restrictions against using contextual string in the password (e.g., user id, app name) Depending on the threat model, the password policy may include several additional attributes. Complex passwords requiring mixed character sets (alpha, numeric, special, mixed case) Increasing the range of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication. Unfortunately, a complex password may be difficult to memorize, encouraging a user to select a short password or to incorrectly manage the password (write it down). Another disadvantage of this approach is that it often does not result in a significant increases in overal password complexity due to people's predictable usage of various symbols. Large Minimum Length (encouraging passphrases instead of passwords) Increasing the number of characters makes the password harder to crack and may be appropriate for systems relying on single factor authentication. A disadvantage of this approach is that selecting a good passphrase is not easy and poor passwords can still be generated. Some prompting may be needed to encourage long un-predictable passwords. Randomly Chosen Secrets Generating a password for the user can help make sure that length and complexity requirements are met, and can result in secure passwords being used. A disadvantage of this approach is that the resulting password or passpharse may be too difficult to memorize, encouraging them to be written down. See NIST 800-63B [REF-1053] for further information on password requirements.
- Architecture and Design: Consider a second authentication factor beyond the password, which prevents the password from being a single point of failure. See CWE-308 for further information.
- Implementation: Consider implementing a password complexity meter to inform users when a chosen password meets the required attributes.
- Implementation: Previously, "password expiration" was widely advocated as a defense-in-depth approach to minimize the risk of weak passwords, and it has become a common practice. Password expiration requires a password to be changed within a fixed time window (such as every 90 days). However, this approach has significant limitations in the current threat landscape, and its utility has been reduced in light of the adoption of related protection mechanisms (such as password complexity and computational effort), along with the recognition that regular password changes often caused users to generate more predictable passwords. As a result, this is now a Discouraged Common Practice [REF-1488] [REF-1489], especially as the sole factor in protecting passwords. It is still strongly encouraged to force password changes in case of evidence of compromise, but this is not the same as a forced "expiration" on an arbitrary time frame.
References
Advisories
Other links
Timeline
- Published
- Added to CISA's Known Exploited Vulnerabilities catalog
- Remediation due for U.S. federal agencies
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-mf5g-6r6f-ghhm OpenClaw: Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Webhook Token | Medium | Same weakness, CWE-521 |
| GHSA-vcx4-4qxg-mfp4 OpenClaw: Telegram Webhook Missing Guess Rate Limiting Enables Brute-Force Guessing of Weak Webhook Secret | Medium | Same weakness, CWE-521 |
| GHSA-xq8g-hgh6-87hv OpenClaw: BlueBubbles Webhook Missing Rate Limiting Enables Brute-Force Password Guessing | Medium | Same weakness, CWE-521 |
| GHSA-3ccg-x393-96v8 Vijkunja has Weak Password Policy Combined with Persistent Sessions After Password Change | Critical | Same weakness, CWE-521 |
| GHSA-5mrf-j8v6-f45g LibreNMS has Weak Password Policy | Low | Same weakness, CWE-521 |
| GHSA-6xj8-rrqx-r4cv MLflow Weak Password Requirements Authentication Bypass Vulnerability | Critical | Same weakness, CWE-521 |
| GHSA-cm2r-rg7r-p7gg File Browser vulnerable to insecure password handling | High | Same weakness, CWE-521 |
| GHSA-4rj2-9gcx-5qhx MLflow has Weak Password Requirements | Medium | Same weakness, CWE-521 |
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