CVE-2021-22038

On Windows, the uninstaller binary copies itself to a fixed temporary location, which is then executed (the originally called uninstaller exits, so it does not block the installation directory). This temporary location is not randomized and does not restrict access to Administrators only so a potential attacker could plant a binary to replace the copied binary right before it gets called, thus gaining Administrator privileges (if the original uninstaller was executed as Administrator). The vulnerability only affects Windows installers.

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

• https://blog.installbuilder.com/2021/10/installbuilder-2160-released.html