Nginx 的网站Log里面有很多奇怪的东西，然后流量爆高，求解疑

Nginx 的网站Log里面有很多奇怪的东西，然后流量爆高，求解疑。
分析下来有2种形式看不懂，第一种如下：
全部都是无浏览器信息，无请求来源的LOG。后面一律是 “- - -”
111.15.17.72 - - [06/Sep/2013:17:21:55 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 69291 - - -
27.27.196.247 - - [06/Sep/2013:17:21:55 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - - -
180.212.57.0 - - [06/Sep/2013:17:21:55 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - - -
119.128.93.100 - - [06/Sep/2013:17:21:56 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - - -
222.184.91.42 - - [06/Sep/2013:17:21:56 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - - -
117.136.23.173 - - [06/Sep/2013:17:21:56 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - - -
113.81.49.227 - - [06/Sep/2013:17:21:57 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - - -


另一种是下面这张，很多16进制编码，应该是中文，但不知如何解码查看。
221.7.7.91 - - [06/Sep/2013:17:21:59 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - \xE4\xBB\x8A\xE6\x97\xA5\xE5\xA4\xB4\xE6\x9D\xA1 2.7 (iPhone; iPhone OS 6.1.3; zh_CN) -
111.20.184.17 - - [06/Sep/2013:17:21:59 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 302187 - \xE5\x86\x85\xE6\xB6\xB5\xE6\xBC\xAB\xE7\x94\xBB 1.3 (iPhone; iPhone OS 6.1.4; zh_CN) -
122.158.78.175 - - [06/Sep/2013:17:21:59 +0800] GET /mh/201309/d9fefd482316eb768eabfdea9fb72128.jpg HTTP/1.1 200 598931 - \xE5\x86\x85\xE6\xB6\xB5\xE6\xBC\xAB\xE7\x94\xBB 1.3 (iPhone; iPhone OS 6.0; zh_CN) -