Bamboo Security Advisory 2014-05-21
This advisory discloses a critical security vulnerability that we have found in Bamboo and fixed in a recent version of Bamboo.
- Customers who have downloaded and installed Bamboo should upgrade their existing Bamboo installations or apply the patch to fix this vulnerability.
- Atlassian OnDemand customers don't have to do anything; they have have been upgraded with the fix for the issue described in this advisory.
- No other Atlassian products are affected.
The vulnerability affects all versions of Bamboo up to and including 5.5.
Atlassian is committed to improving product security. We fully support the reporting of vulnerabilities and we appreciate it when people work with us to identify and solve the problem.
If you have questions or concerns regarding this advisory, please raise a support request at http://support.atlassian.com.
ClassLoader manipulation vulnerability
Severity
Atlassian rates the severity level of this vulnerability as critical, according to the scale published in Severity Levels of Security Issues. The scale allows us to rank the severity as critical, high, moderate or low.
This is an independent assessment and you should evaluate its applicability to your own IT environment.
Description
We have fixed a vulnerability in our fork of Apache Struts. Attackers can use this vulnerability to execute Java code of their choice on systems that use these frameworks. The attacker needs to be able to access the Bamboo web interface. In cases when anonymous access is enabled, a valid user account is not required to exploit this vulnerability.
We have discovered this vulnerability during our review of the recent Struts security advisories. This vulnerability is specific to Bamboo.
The vulnerability affects all versions of Bamboo up to and including 5.5. Bamboo 5.6 is not vulnerable. The issue is tracked in BAM-14571 - Getting issue details... STATUS
Risk Mitigation
If you are unable to upgrade your Bamboo server you can do the following as a temporary workaround:
Block at a reverse proxy or a firewall all requests matching the following regular expression pattern in URI parameters. Note that the example does not account for any URL encoding that may be present.
.*[?&](.*\.||.*|\[('|"))(c|C)lass(\.|('|")]|\[).*
Fix
This vulnerability can be fixed by upgrading Bamboo to version 5.4.3, 5.5.1, or the upcoming 5.6. There is also a patch available for this vulnerability for all supported versions of Bamboo. We recommend upgrading.
The Security Patch Policy describes when and how we release security patches and security upgrades for our products.
Upgrading Bamboo
Upgrade to Bamboo 5.4.3, 5.5.1, 5.6 or a later version, which fixes this vulnerability. For a full description of these releases, see the Bamboo Release Notes. You can download these versions of Bamboo from the download centre.
Patches
We recommend patching only when you cannot upgrade or cannot apply external security controls. Patches are usually only provided for vulnerabilities of critical severity (as per our Security Patch Policy) as an interim solution until you can upgrade. You should not expect that you can continue patching your system instead of upgrading. Our patches are often non-cumulative – we do not recommend that you apply multiple patches from different advisories on top of each other, but strongly recommend upgrading to the most recent version regularly.
If for some reason you cannot upgrade to the latest version of Bamboo, you must apply the patch provided below to fix the vulnerability described in this advisory. It has been tested for all supported versions of Bamboo and may work for unsupported versions as well.
Download the patch file.
VersionPatchTracking issueMD5 Bamboo 5.1-5.5 atlassian-xwork-12-1.17-xwork2-1.jar BAM-14571 - Getting issue details... STATUS 478b5877510e34d11d09f8635e292564
Bamboo pre-5.1 atlassian-xwork-12-1.17.jar BAM-14571 - Getting issue details... STATUS 1dd1308afdd146feafe626daee73e299
- Shut down Bamboo.
- Move file
<BAMBOO_INSTALL>/atlassian-bamboo/WEB-INF/lib/atlassian-xwork-12-x.x.jarto a location outside the<Bamboo-INSTALL>folder. - Add the downloaded patched jar file to folder
<Bamboo-INSTALL>/atlassian-bamboo/WEB-INF/lib/. Start up Bamboo again.