Use of Cryptographically Weak Pseudo-Random Number Generator in Rclone

Description

An issue was discovered in Rclone before 1.53.3. Due to the use of a weak random number generator, the password generator has been producing weak passwords with much less entropy than advertised. The suggested passwords depend deterministically on the time the second rclone was started. This limits the entropy of the passwords enormously. These passwords are often used in the crypt backend for encryption of data. It would be possible to make a dictionary of all possible passwords with about 38 million entries per password length. This would make decryption of secret material possible with a plausible amount of effort. NOTE: all passwords generated by affected versions should be changed.

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Source code
Browse source ↗
Published (advisory)
2021-06-10 17:23:21 UTC
Updated
2023-02-01 05:06:08 UTC
GitHub reviewed
2021-06-09 14:47:19 UTC
NVD published
2020-11-19

EPSS Score

Score Percentile
0.35% 57.51%

CVSS Scores

Base score Version Severity Vector
7.5 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-331 Insufficient Entropy
CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/rclone/rclone < 1.53.3 1.53.3

References

cvelogic Threat Intelligence