发现漏洞
一个多月后，我就发现了存在facebook ads广告业务系统api中的一个漏洞。存在漏洞的api是一个图片处理接口，它用于facebook商户账户上传广告图片，上传的图片会储存在一个名为“/adimages”的目录下，并用base64格式编码。所以，我的测试构想是，在这里的机制中，可以向上传图片中注入恶意payload，经api转换为 base64 格式后，再被facebook传入服务器中。
以下为上传图片的POST请求：
POST /v2.10/act_123456789/adimages HTTP/1.1Host: graph.facebook.comBytes=VGhpcyBpcyBtYWxpY2lvdXMgcGF5bG9hZC4=
由于Facebook服务器端不能有效地处理恶意Payload图片，最终其“Image Resizing Tool”图片处理工具返回了一个报错，在某个JSON响应内容的异常消息中，就包括了一些PHP库函数代码，这些代码来自不同的Facebook库文件，可以肯定的是，这应该属于Facebook源代码的一部份。
HTTP/1.1 200 OK{“error”:{“message”:”Invalid parameter”,”type”:”FacebookApiException”,”code”:100,”error_data”:”exception ‘Exception’ with message ‘gen_image_rescale_multi_thrift call to shrinkImageMulti failed with fbalgo exception: 43 (43: : IDAT: invalid distance too far back)’ in \/var\/www\/flib\/resource\/filesystem\/upload\/upload.php:1393\nStack trace:\n#0 \/var\/www\/flib\/resource\/filesystem\/upload\/upload.php(1662): gen_image_rescale_multi_thrift()\n#1 \/var\/www\/flib\/ads\/admanager\/adupload\/adupload.php(252): gen_image_rescale_multi()\n#2 \/var\/www\/flib\/ads\/admanager\/adupload\/AdImageUtils.php(195): _gen_adupload_image_resize()\n#3 \/var\/www\/flib\/ads\/entities\/creatives\/photos\/AdproCreativePhotoDownload.php(53): AdImageUtils::genResizeLocalFile()\n#4 \/var\/www\/flib\/platform\/graph\/resources\/adaccount\/adimages\/mutators\/GraphAdAccountAdImagesPost.php(134): AdproCreativePhotoDownload::addLocalFileToCreativeLibrary()\n#5 \/var\/www\/flib\/core\/data_structures\/utils\/Arrays.php(440): Closure$GraphAdAccountAdImagesPost::genImplementation#3()\n#6 \/var\/www\/flib\/platform\/graph\/resources\/adaccount\/adimages\/mutators\/GraphAdAccountAdImagesPost.php(136): Arrays::genMapWithKey()\n#7 \/var\/www\/flib\/ads\/api\/graph_base\/GraphAdsWriteWithRedirectBase.php(22): GraphAdAccountAdImagesPost->genImplementation()\n#8 \/var\/www\/flib\/ads\/api\/graph_base\/GraphAdsWriteWithRedirectBase.php(11): GraphAdsWriteWithRedirectBase->genDoCall()\n#9 \/var\/www\/flib\/core\/asio\/gen_utils.php(24): GraphAdsWriteWithRedirectBase->genCall()\n#10 \/var\/www\/flib\/platform\/api\/base\/ApiBaseWithTypedApiData.php(204): genw()\n#11 \/var\/www\/flib\/platform\/api\/base\/ApiBase.php(85): ApiBaseWithTypedApiData->genCallWithApiDataBase()\n#12 \/var\/www\/flib\/platform\/graph\/core\/runner\/GraphApiRunnerBase.php(373): ApiBase->genMakeCall()\n#13 \/var\/www\/flib\/platform\/graph\/core\/GraphRequestProcessorBase.php(629): GraphApiRunnerBase->genCall()\n#14 \/var\/www\/flib\/platform\/graph\/core\/GraphRequestProcessorBase.php(45): GraphRequestProcessorBase->genExecuteSingleGraphRequestCore()\n#15 \/var\/www\/api\/graph\/server.php(168): GraphRequestProcessorBase->genExecuteSingleGraphRequest()\n#16 \/var\/www\/api\/graph\/server.php(174): gen_api_graph_server()\n#17 \/var\/www\/flib\/core\/asio\/Asio.php(35): gen_api_graph_server_wrapper()\n#18 (): Closure$Asio::enterAsyncEntryPoint()\n#19 \/var\/www\/flib\/core\/asio\/Asio.php(37): HH\\Asio\\join()\n#20 \/var\/www\/api\/graph\/server.php(180): Asio::enterAsyncEntryPoint()\n#21 {main}”,”error_subcode”:1487242,”is_transient”:false,”error_user_title”:”Image Resize Failed”,”error_user_msg”:”Image Resize Failed:unknown reason”,”fbtrace_id”:”EN\/o9hmqwZz”},”__fb_trace_id__”:”EN\/o9hmqwZz”} 
