strange {"OK":{}} response on ElasticSearch curl -X GET 'http://localhost:9200' - elasticsearch

Question

On one on my nodes in my ElasticSearch cluster I get the following strange response:
Command:
curl -X GET 'http://localhost:9200'
Response:
{"OK":{}}
Not sure what to do about this? Anyone run into this before?
UPDATE:
This is what I get when I call (I replaced IP's with xxx):
curl -XGET localhost:9200/_nodes/jvm?human\&pretty
{
"cluster_name" : "elasticsearch",
"nodes" : {
"dtUV63D4RBq9JXw_o03-eg" : {
"name" : "elasticsearch1",
"transport_address" : "inet[xxx/xxx:9300]",
"host" : "elasticsearch1",
"ip" : "xxx",
"version" : "1.3.2",
"build" : "dee175d",
"http_address" : "inet[/xxx:9200]",
"jvm" : {
"pid" : 1471,
"version" : "1.7.0_65",
"vm_name" : "OpenJDK 64-Bit Server VM",
"vm_version" : "24.65-b04",
"vm_vendor" : "Oracle Corporation",
"start_time" : "2014-11-19T14:50:10.408Z",
"start_time_in_millis" : 1416408610408,
"mem" : {
"heap_init" : "4gb",
"heap_init_in_bytes" : 4294967296,
"heap_max" : "3.9gb",
"heap_max_in_bytes" : 4277534720,
"non_heap_init" : "23.1mb",
"non_heap_init_in_bytes" : 24313856,
"non_heap_max" : "214mb",
"non_heap_max_in_bytes" : 224395264,
"direct_max" : "3.9gb",
"direct_max_in_bytes" : 4277534720
},
"gc_collectors" : [ "ParNew", "ConcurrentMarkSweep" ],
"memory_pools" : [ "Code Cache", "Par Eden Space", "Par Survivor Space", "CMS Old Gen", "CMS Perm Gen" ]
}
},
"8eGVx6IGQ8qiFTc4rnaG3A" : {
"name" : "elasticsearch2",
"transport_address" : "inet[/xxx:9300]",
"host" : "elasticsearch2",
"ip" : "xxx",
"version" : "1.3.2",
"build" : "dee175d",
"http_address" : "inet[/xxx:9200]",
"jvm" : {
"pid" : 1476,
"version" : "1.7.0_65",
"vm_name" : "OpenJDK 64-Bit Server VM",
"vm_version" : "24.65-b04",
"vm_vendor" : "Oracle Corporation",
"start_time" : "2014-11-19T14:54:33.909Z",
"start_time_in_millis" : 1416408873909,
"mem" : {
"heap_init" : "4gb",
"heap_init_in_bytes" : 4294967296,
"heap_max" : "3.9gb",
"heap_max_in_bytes" : 4277534720,
"non_heap_init" : "23.1mb",
"non_heap_init_in_bytes" : 24313856,
"non_heap_max" : "214mb",
"non_heap_max_in_bytes" : 224395264,
"direct_max" : "3.9gb",
"direct_max_in_bytes" : 4277534720
},
"gc_collectors" : [ "ParNew", "ConcurrentMarkSweep" ],
"memory_pools" : [ "Code Cache", "Par Eden Space", "Par Survivor Space", "CMS Old Gen", "CMS Perm Gen" ]
}
}
}
}

Answer 1

Elasticsearch 1.3.2 alone is not capable of producing such response - there is simply no "OK" string in the production source code. So, I would guess somebody installed a plugin on this node that intercepts some calls and replaces them with this message.
One of the plugins that does that is elasticsearch-http-basic plugin, which indeed displays {"OK":{}} to unauthorized users instead of a full response. You can verify presence of this and other plugins by executing the following command on the node that gives you responses:
curl "localhost:9200/_nodes/plugins?pretty"