Обнаружил в логах такой запрос:
93.84.40.104 example.org - [08/Nov/2011:21:01:12 +0400] "GET /2010/09/url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEYAAAAOCAYAAACSJWqFAAAABGdBTUEAALGPC%2fxhBQAAAAlwSFlzAAALEgAACxIB0t1%2b%2fAAAAAd0SU1FB9oGAhENK17O5ogAAAAZdEVYdENvbW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAGXRFWHRTb2Z0d2FyZQBQYWludC5ORVQgdjMuNS44NzuAXQAAA99JREFUSMfdlmtMm1UYx%2fkOM1vmBck2EIyZOiLZJRLlMhaXhQSjmRiHiVmi7gKpjshlBAiMhYG0C3UdinyYCUYMgm6MsYVLuV%2fLaArl1pYWGLQwJ6OIEeKnn%2bcdZc4CS6vDyJ7kn%2feck5Nz3vPL%2f3nO8fDYIDFpnwsZvjPL2Ss38T9eTFTmdzT0ahi9paUmJgKNvxejfl6M%2b3phFt8BX0%2b0vp4hHo97WO1zNJtvE5rdyLOJbXjHVZBbpsZo1TPSUIY%2byIdxAWRMyCSk932CTj9PHsnmcRk%2f%2bgv1COGQ1N7zfwAztbBIrWGKoKwWfFJv8vSpBqIVlWiNOkaH2tBGBWPxW3KNwXcTOvFtE3pUYN4QqhPa4uhLbct6HfaCUsmF%2fPwVPy%2bNOY%2fbFhZoH79DZH4nPkkd%2bCS0E5lbg2aoF4OuhcZDQbTt2kxL4Fbad26mS6RWk9%2bmv60RILciyXm%2fAIUYV1hxB9RpyTnrBsYBQALkDEv1wJgUgz%2ffxXB3jqzKAQKSGtnxWRMJpVq6BnUoFbnEhu7lZOgrfPD%2bXg7HvYTsyPOogp9iJQDbPTlDcRmM5BpHKpWtZ4pIAFQOGPegrOGi44X11A9PoLXNUNAwgrLOIPpjpJ3JoOr6DVo1AlJ3D58X5PFCShjbFK%2bzK%2fXVVdxh4y9A7kORUsriALPFhfk8TC47Z5UUWo6X4y8TlnaZ%2bEtqrvWZsPxqJ1ueR8XVq0zMLlCsn6dk8Hc6zb%2bQcz6HgPT9bJWHrbqWBMJf7iaUB2pLkavzk5Q%2f%2bT1MboFxSqHl2PdpKYGycnbGlpJW0olRpFVCSgrmyWkuaueZ%2fe0PrFN2SnR26scXkZ%2fPZ1tu%2bKpr3YciXwK0bmD%2bdZ1ZTiVHbVkNzlvpPyD7Ss3Zsg6%2bb%2b1FP2lBdkrG6ISNIq0d48g0tW0mCppttEwskph8Gu%2bs8DUL7X3XuAvnP4PiVGhVa9SZmn4LA5NGBkzl9Pcp6OlKISP9JDcqK%2flGgPm2eZxLHdMoNPOUNunIPJPF9nMHVtxKS25xLr421%2bA4HFO37mDcuK7NM5NoWtPR1gQz1BDIoDqQ8qJDvPfum3SIwlthWqB2bJHi2m4%2b%2fPgYkZ%2fE8ExmBK5cy86wNlQM3eqh48p%2bTOog8dINwqjeTX%2fVPgrPHSQ5OZmcPAVfXPyS9IS3UaX6Ex0bwZPxoRvzsO6E6baZ7usxDAkYw9XBGKpfw1gVTp86kbpujbit5LyY9g4HThwkP8mH6q%2bf4%2fBHkY8%2fGMuMNcQ42sxAU5IAc5ThmqOY2nOwTA9zTbx%2b9yhP4K2IZnv2EaJk0ahSvKku3PGPwfwJAW1Er1YzJJgAAAAASUVORK5CYII%3d) HTTP/1.1" 404 345 "http://example.org/2010/09/27.html" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; GTB7.1; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E)"
Что они пытались сделать, интересно? Расшифровал этот base64, там это png.