Increased Lambda costs via multipart header parsing
Published Mar 22, 2024 · Updated Aug 28, 2024
Resource consumption in Bref before 2.1.17 allows remote attackers to increase AWS Lambda execution time via multipart POST requests. StreamedPart::parseHeaderContent passes an attacker-controlled multipart Content-Type value as both the input string and source encoding to mb_convert_encoding, causing expensive multibyte operations on oversized headers. Exposure requires an Event-Driven Function using a RequestHandlerInterface and a POST endpoint; one crafted body can raise billed duration from under 200 ms to over 400 ms.
Summary
What happened
Resource consumption in Bref before 2.1.17 allows remote attackers to increase AWS Lambda execution time via multipart POST requests. StreamedPart::parseHeaderContent passes an attacker-controlled multipart Content-Type value as both the input string and source encoding to mb_convert_encoding, causing expensive multibyte operations on oversized headers. Exposure requires an Event-Driven Function using a RequestHandlerInterface and a POST endpoint; one crafted body can raise billed duration from under 200 ms to over 400 ms.
The record
- CVE
- CVE-2024-29186
- Published
- Mar 22, 2024
- Updated
- Aug 28, 2024
- Vendor
- Bref
- Product
- Bref
- Classifications
- CWE-400, T1496
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 22, 2024CVE publishedPublication date reported by the CVE source.
- Aug 28, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <2.1.17
- Affected versionversion=< 2.1.17
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Bref multipart Content-Type proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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