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Angular Expressions - Remote Code Execution

High severity GitHub Reviewed Published Jan 29, 2021 in peerigon/angular-expressions • Updated Feb 1, 2023

Package

npm angular-expressions (npm)

Affected versions

< 1.1.2

Patched versions

1.1.2

Description

Impact

The vulnerability, reported by GoSecure Inc, allows Remote Code Execution, if you call expressions.compile(userControlledInput) where userControlledInput is text that comes from user input.

This time, the security of the package could be bypassed by using a more complex payload, using a .constructor.constructor technique.

  • If running angular-expressions in the browser, an attacker could run any browser script when the application code calls expressions.compile(userControlledInput).
  • If running angular-expressions on the server, an attacker could run any Javascript expression, thus gaining Remote Code Execution.

Patches

Users should upgrade to version 1.1.2 of angular-expressions

Workarounds

A temporary workaround might be either to :

  • disable user-controlled input that will be fed into angular-expressions in your application

OR

  • allow only following characters in the userControlledInput :
if (/^[|a-zA-Z.0-9 :"'+-?]+$/.test(userControlledInput)) {
      var result = expressions.compile(userControlledInput);
}
else {
     result = undefined;
}

References

Removal of angular-expression sandbox

For more information

If you have any questions or comments about this advisory:

Credits

The issue was reported by Maxime Nadeau from GoSecure, Inc.

References

@edi9999 edi9999 published to peerigon/angular-expressions Jan 29, 2021
Reviewed Feb 1, 2021
Published to the GitHub Advisory Database Feb 1, 2021
Published by the National Vulnerability Database Feb 1, 2021
Last updated Feb 1, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS score

0.913%
(83rd percentile)

CVE ID

CVE-2021-21277

GHSA ID

GHSA-j6px-jwvv-vpwq

Source code

No known source code
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