GHSA-fr32-gr5c-xq5c CVE-2019-8321
RubyGems Escape sequence injection vulnerability in verbose
High
RubyGems
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 3.28%
- Chance of exploitation in the next 30 days. Higher than 88.45% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-88 Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
- Fix
2.7.9- Upgrade rubygems-update to this version or later
Description
An issue was discovered in RubyGems 2.6 and later through 3.0.2. Since Gem::UserInteraction#verbose calls say without escaping, escape sequence injection is possible.
Affected versions
RubyGems
| Package | Vulnerable | Fixed in |
|---|---|---|
| rubygems-update | >= 2.6.0, < 2.7.9 |
2.7.9 |
| rubygems-update | >= 3.0.0, < 3.0.2 |
3.0.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
rubygems-update RubyGems → 2.7.9
- bundler
bundle update rubygems-update # Gemfile: gem "rubygems-update", ">= 2.7.9"
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Weakness
CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
How to prevent it
- Implementation: Where possible, avoid building a single string that contains the command and its arguments. Some languages or frameworks have functions that support specifying independent arguments, e.g. as an array, which is used to automatically perform the appropriate quoting or escaping while building the command. For example, in PHP, escapeshellarg() can be used to escape a single argument to system(), or exec() can be called with an array of arguments. In C, code can often be refactored from using system() - which accepts a single string - to using exec(), which requires separate function arguments for each parameter.
- Architecture and Design: Understand all the potential areas where untrusted inputs can enter your product: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the application. Perform input validation at well-defined interfaces.
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- Implementation: Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
- Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
- Implementation: When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
- Testing: Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
References
Advisories
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-228f-g3h7-3fj3 RubyGems HTTPS to HTTP redirect | Medium | Also affects rubygems-update |
| GHSA-5mgj-mvv8-46mw RubyGems does not verify SSL certificate | Medium | Also affects rubygems-update |
| GHSA-qv62-xfj6-32xm RubyGems Improper Input Validation vulnerability | Medium | Also affects rubygems-update |
| GHSA-9qvm-2vhf-q649 RubyGems Regular Expression Denial of Service | Medium | Also affects rubygems-update |
| GHSA-8qxg-mff5-j3wc RubyGems Path Traversal vulnerability | Medium | Also affects rubygems-update |
| GHSA-wp3j-rvfp-624h RubyGems vulnerable to DNS hijack attack | High | Also affects rubygems-update |
| GHSA-9j7m-rjqx-48vh RubyGems Regular Expression Denial of Service vulnerability | Medium | Also affects rubygems-update |
| GHSA-p7f2-rr42-m9xm RubyGems Improper Input Validation vulnerability | High | Also affects rubygems-update |
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