Horizon Alert
Summary of the vulnerability and why it matters
A vulnerability in the sift.js JavaScript library allows for arbitrary code execution if a prototype pollution primitive is used to inject malicious code into the query object. This means that even standard filtering operations could be hijacked to run unintended scripts, posing a significant risk to applications using this library without proper safeguards. The primary concern is confirming whether this library is used and if the affected functionality is exposed to untrusted input.
- Unsanitized queries in a JavaScript library can run malicious code.
- It could impact applications filtering user-provided data.
- Confirm if this library is used and how data is filtered.
Attack Path
How an attacker could exploit the issue
An attacker could trigger arbitrary JavaScript execution by manipulating the `sift.js` library. This occurs when an attacker can either pollute the object prototype chain to control the `$where` operator or directly inject a malicious string into the `$where` field of a query passed to `sift`. The library then compiles this string into executable code by default, leading to code execution.
- Unauthenticated network access required.
- Malicious query object or prototype pollution.
- Arbitrary JavaScript code execution.
Live Threat
Current exploitation, exposure, and threat context
When sift.js processes query keys using a `for...in` loop, it traverses the object's prototype chain. If an attacker can manipulate the prototype chain to inject a malicious string into the `$where` operator, any subsequent call to `sift` with a benign query could execute arbitrary JavaScript. This could occur when processing untrusted query objects directly or when the prototype pollution occurs elsewhere in the application.
- Arbitrary JavaScript execution.
- Prototype pollution to inject code.
- Application compromise and data theft.
Operational Fix
Recommended remediation, mitigation, and detection steps
Application owners and platform teams should prioritize understanding the impact of this vulnerability. The first practical step is to identify all instances of the affected JavaScript library, determine their reachability and criticality, and then assign ownership for remediation or risk mitigation.
- Application owners should address this.
- Verify all sift.js deployments.
- Plan remediation during maintenance windows.
