Archive for the ‘TCP’ tag

Probes towards TCP/37777  

Posted at 8:43 am in Uncategorized

Seems a new bot, possibly a strain of Mirai, is in the wild, targeting TCP port 37777. The last 24 hours I’ve seen close to 200 different IP addresses trying to connect to this port. DShield is also registering an increase.

At the moment I can only guess what kind of product they’re probing for, but looking up the port results in quite a few hits regarding remote access to DVRs (Digital Video Recorders) and IP cameras. Some of the links indicate that this could be the Q-See products. The request below seems to map perfectly to uploading UPnP config to AmCrest and/or Dahua based cameras.

Allowing the probes access to my honeypot gives me the the chance to analyze the request, which in essence looks like this:

{
  "Enable": 1,
  "MapTable": [
    {
      "Enable": 1,
      "InnerPort": 85,
      "OuterPort": 85,
      "Protocol": "TCP",
      "ServiceName": "HTTP"
    },
    {
      "Enable": 1,
      "InnerPort": 37777,
      "OuterPort": 37777,
      "Protocol": "TCP",
      "ServiceName": "TCP"
    },
    {
      "Enable": 1,
      "InnerPort": 37778,
      "OuterPort": 37778,
      "Protocol": "UDP",
      "ServiceName": "UDP"
    },
    {
      "Enable": 1,
      "InnerPort": 554,
      "OuterPort": 554,
      "Protocol": "TCP",
      "ServiceName": "RTSP"
    },
    {
      "Enable": 1,
      "InnerPort": 23,
      "OuterPort": 23231,
      "Protocol": "TCP",
      "ServiceName": "TELNET"
    },
    {
      "Enable": 1,
      "InnerPort": 23,
      "OuterPort": 23123,
      "Protocol": "TCP",
      "ServiceName": "NEW"
    }
  ]
}

 

Looks pretty much like someone’s trying to enable remote access through inbound NAT, using a UPnP config. I’ve found the fields in the UPnP requests in documentation from Dahua and AmCrest. Speculation only at this time, but this could be for allowing shell access to a unit that’s so far been configured for HTTP access only.

Note that the OuterPort for telnet access maps nicely to what we’ve seen from Mirai bots earlier. With this config sample we should also keep our eyes open on TCP ports 85 and 23123 as well.

Hex dump of the request:

00000000 c1 00 00 00 00 14 00 00 63 6f 6e 66 69 67 00 00 ........ config..
00000010 31 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1....... ........
00000020 7b 20 22 45 6e 61 62 6c 65 22 20 3a 20 31 2c 20 { "Enabl e" : 1, 
00000030 22 4d 61 70 54 61 62 6c 65 22 20 3a 20 5b 20 7b "MapTabl e" : [ {
00000040 20 22 45 6e 61 62 6c 65 22 20 3a 20 31 2c 20 22 "Enable " : 1, "
00000050 49 6e 6e 65 72 50 6f 72 74 22 20 3a 20 38 35 2c InnerPor t" : 85,
00000060 20 22 4f 75 74 65 72 50 6f 72 74 22 20 3a 20 38 "OuterP ort" : 8
00000070 35 2c 20 22 50 72 6f 74 6f 63 6f 6c 22 20 3a 20 5, "Prot ocol" : 
00000080 22 54 43 50 22 2c 20 22 53 65 72 76 69 63 65 4e "TCP", " ServiceN
00000090 61 6d 65 22 20 3a 20 22 48 54 54 50 22 20 7d 2c ame" : " HTTP" },
000000A0 20 7b 20 22 45 6e 61 62 6c 65 22 20 3a 20 31 2c { "Enab le" : 1,
000000B0 20 22 49 6e 6e 65 72 50 6f 72 74 22 20 3a 20 33 "InnerP ort" : 3
000000C0 37 37 37 37 2c 20 22 4f 75 74 65 72 50 6f 72 74 7777, "O uterPort
000000D0 22 20 3a 20 33 37 37 37 37 2c 20 22 50 72 6f 74 " : 3777 7, "Prot
000000E0 6f 63 6f 6c 22 20 3a 20 22 54 43 50 22 2c 20 22 ocol" : "TCP", "
000000F0 53 65 72 76 69 63 65 4e 61 6d 65 22 20 3a 20 22 ServiceN ame" : "
00000100 54 43 50 22 20 7d 2c 20 7b 20 22 45 6e 61 62 6c TCP" }, { "Enabl
00000110 65 22 20 3a 20 31 2c 20 22 49 6e 6e 65 72 50 6f e" : 1, "InnerPo
00000120 72 74 22 20 3a 20 33 37 37 37 38 2c 20 22 4f 75 rt" : 37 778, "Ou
00000130 74 65 72 50 6f 72 74 22 20 3a 20 33 37 37 37 38 terPort" : 37778
00000140 2c 20 22 50 72 6f 74 6f 63 6f 6c 22 20 3a 20 22 , "Proto col" : "
00000150 55 44 50 22 2c 20 22 53 65 72 76 69 63 65 4e 61 UDP", "S erviceNa
00000160 6d 65 22 20 3a 20 22 55 44 50 22 20 7d 2c 20 7b me" : "U DP" }, {
00000170 20 22 45 6e 61 62 6c 65 22 20 3a 20 31 2c 20 22 "Enable " : 1, "
00000180 49 6e 6e 65 72 50 6f 72 74 22 20 3a 20 35 35 34 InnerPor t" : 554
00000190 2c 20 22 4f 75 74 65 72 50 6f 72 74 22 20 3a 20 , "Outer Port" : 
000001A0 35 35 34 2c 20 22 50 72 6f 74 6f 63 6f 6c 22 20 554, "Pr otocol" 
000001B0 3a 20 22 54 43 50 22 2c 20 22 53 65 72 76 69 63 : "TCP", "Servic
000001C0 65 4e 61 6d 65 22 20 3a 20 22 52 54 53 50 22 20 eName" : "RTSP" 
000001D0 7d 2c 20 7b 20 22 45 6e 61 62 6c 65 22 20 3a 20 }, { "En able" : 
000001E0 31 2c 20 22 49 6e 6e 65 72 50 6f 72 74 22 20 3a 1, "Inne rPort" :
000001F0 20 32 33 2c 20 22 4f 75 74 65 72 50 6f 72 74 22 23, "Ou terPort"
00000200 20 3a 20 32 33 32 33 31 2c 20 22 50 72 6f 74 6f : 23231 , "Proto
00000210 63 6f 6c 22 20 3a 20 22 54 43 50 22 2c 20 22 53 col" : " TCP", "S
00000220 65 72 76 69 63 65 4e 61 6d 65 22 20 3a 20 22 54 erviceNa me" : "T
00000230 45 4c 4e 45 54 22 20 7d 2c 20 7b 20 22 45 6e 61 ELNET" } , { "Ena
00000240 62 6c 65 22 20 3a 20 31 2c 20 22 49 6e 6e 65 72 ble" : 1 , "Inner
00000250 50 6f 72 74 22 20 3a 20 32 33 2c 20 22 4f 75 74 Port" : 23, "Out
00000260 65 72 50 6f 72 74 22 20 3a 20 32 33 31 32 33 2c erPort" : 23123,
00000270 20 22 50 72 6f 74 6f 63 6f 6c 22 20 3a 20 22 54 "Protoc ol" : "T
00000280 43 50 22 2c 20 22 53 65 72 76 69 63 65 4e 61 6d CP", "Se rviceNam
00000290 65 22 20 3a 20 22 4e 45 57 22 20 7d 20 5d 20 7d e" : "NE W" } ] }
000002A0 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........

 

(More zero padding below)

UPDATE: This could be based on a four year old vulnerability with Dahua devices: http://cve.circl.lu/cve/CVE-2013-6117

Written by bjorn on January 10th, 2017

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