Executive Summary
Informations | |||
---|---|---|---|
Name | CVE-2021-27850 | First vendor Publication | 2021-04-15 |
Vendor | Cve | Last vendor Modification | 2021-06-02 |
Security-Database Scoring CVSS v3
Cvss vector : CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | |||
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Overall CVSS Score | 9.8 | ||
Base Score | 9.8 | Environmental Score | 9.8 |
impact SubScore | 5.9 | Temporal Score | 9.8 |
Exploitabality Sub Score | 3.9 | ||
Attack Vector | Network | Attack Complexity | Low |
Privileges Required | None | User Interaction | None |
Scope | Unchanged | Confidentiality Impact | High |
Integrity Impact | High | Availability Impact | High |
Calculate full CVSS 3.0 Vectors scores |
Security-Database Scoring CVSS v2
Cvss vector : (AV:N/AC:L/Au:N/C:C/I:C/A:C) | |||
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Cvss Base Score | 10 | Attack Range | Network |
Cvss Impact Score | 10 | Attack Complexity | Low |
Cvss Expoit Score | 10 | Authentication | None Required |
Calculate full CVSS 2.0 Vectors scores |
Detail
A critical unauthenticated remote code execution vulnerability was found all recent versions of Apache Tapestry. The affected versions include 5.4.5, 5.5.0, 5.6.2 and 5.7.0. The vulnerability I have found is a bypass of the fix for CVE-2019-0195. Recap: Before the fix of CVE-2019-0195 it was possible to download arbitrary class files from the classpath by providing a crafted asset file URL. An attacker was able to download the file `AppModule.class` by requesting the URL `http://localhost:8080/assets/something/services/AppModule.class` which contains a HMAC secret key. The fix for that bug was a blacklist filter that checks if the URL ends with `.class`, `.properties` or `.xml`. Bypass: Unfortunately, the blacklist solution can simply be bypassed by appending a `/` at the end of the URL: `http://localhost:8080/assets/something/services/AppModule.class/` The slash is stripped after the blacklist check and the file `AppModule.class` is loaded into the response. This class usually contains the HMAC secret key which is used to sign serialized Java objects. With the knowledge of that key an attacker can sign a Java gadget chain that leads to RCE (e.g. CommonsBeanUtils1 from ysoserial). Solution for this vulnerability: * For Apache Tapestry 5.4.0 to 5.6.1, upgrade to 5.6.2 or later. * For Apache Tapestry 5.7.0, upgrade to 5.7.1 or later. |
Original Source
Url : http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-27850 |
CWE : Common Weakness Enumeration
% | Id | Name |
---|---|---|
100 % | CWE-502 | Deserialization of Untrusted Data |
CPE : Common Platform Enumeration
Type | Description | Count |
---|---|---|
Application | 1 |
Metasploit Database
id | Description |
---|---|
2021-04-15 | Apache Tapestry HMAC secret key leak |
Sources (Detail)
Alert History
Date | Informations |
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2021-07-22 21:23:08 |
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2021-06-02 21:23:18 |
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2021-05-28 17:22:57 |
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2021-05-04 14:09:53 |
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2021-04-22 17:22:46 |
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2021-04-15 17:23:00 |
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2021-04-15 13:23:14 |
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