CVE-2020-2099

Jenkins 2.213 and earlier, LTS 2.204.1 and earlier improperly reuses encryption key parameters in the Inbound TCP Agent Protocol/3, allowing unauthorized attackers with knowledge of agent names to obtain the connection secrets for those agents, which can be used to connect to Jenkins, impersonating those agents.

Weakness

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

Affected Software

Potential Mitigations

• Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds.
• In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts.
• Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a “random enough” number.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/112.html
• https://cwe.mitre.org/data/definitions/485.html
• https://cwe.mitre.org/data/definitions/59.html

References

• http://www.openwall.com/lists/oss-security/2020/01/29/1
• https://access.redhat.com/errata/RHBA-2020:0402
• https://access.redhat.com/errata/RHBA-2020:0675
• https://access.redhat.com/errata/RHSA-2020:0681
• https://access.redhat.com/errata/RHSA-2020:0683
• https://jenkins.io/security/advisory/2020-01-29/#SECURITY-1682