CVE-2021-39195 (published 2021-09-07T19:15Z)

Misskey is an open source, decentralized microblogging platform. In affected versions a Server-Side Request Forgery vulnerability exists in "Upload from URL" and remote attachment handling. This could result in the disclosure of non-public information within the internal network. This has been fixed in 12.90.0. However, if you are using a proxy, you will need to take additional measures. As a workaround this exploit may be avoided by appropriately restricting access to private networks from the host where the application is running.

Severity: MEDIUM
CVSS v2 base score: 4.0 (AV:N/AC:L/Au:S/C:P/I:N/A:N)
CVSS v3 base score: 6.5, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)

Weakness information:
cwe_id: CWE-918
cwe_name: Server-Side Request Forgery (SSRF)
description: The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
extended_description: By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
         

Fix information:
repo_url: https://github.com/misskey-dev/misskey
commit_details: repo_url: https://github.com/misskey-dev/misskey
author: MeiMei
author_date: 2021-09-03 21:00:44+09:00
msg: Tune download (#2)

* s2-2

* allowedPrivateNetworks

* style

* Proxyの間にあると誤解しそうなのでconfigの記述順を変更

* Fix error handler
repository: repo_url: https://github.com/misskey-dev/misskey
repo_name: misskey-dev/misskey
description: 🌎 An interplanetary microblogging platform 🚀
repo_language: TypeScript
owner: misskey-dev
file_changes: filename: example.yml
change_type: ModificationType.MODIFY
diff: @@ -157,3 +157,7 @@ id: 'aid'
 
 # Sign to ActivityPub GET request (default: false)
 #signToActivityPubGet: true
+
+#allowedPrivateNetworks: [
+#  '127.0.0.1/32'
+#]

programming_language: Markdown
filename: package.json
change_type: ModificationType.MODIFY
diff: @@ -148,6 +148,7 @@
 		"http-signature": "1.3.5",
 		"idb-keyval": "5.1.3",
 		"insert-text-at-cursor": "0.3.0",
+		"ip-cidr": "3.0.4",
 		"is-svg": "4.3.1",
 		"js-yaml": "4.1.0",
 		"jsdom": "16.7.0",
@@ -184,6 +185,7 @@
 		"postcss": "8.3.6",
 		"postcss-loader": "6.1.1",
 		"prismjs": "1.24.1",
+		"private-ip": "2.2.1",
 		"probe-image-size": "7.2.1",
 		"promise-limit": "2.7.0",
 		"pug": "3.0.2",

programming_language: Go
filename: types.ts
change_type: ModificationType.MODIFY
diff: @@ -37,6 +37,8 @@ export type Source = {
 	proxySmtp?: string;
 	proxyBypassHosts?: string[];
 
+	allowedPrivateNetworks?: string[];
+
 	accesslog?: string;
 
 	clusterLimit?: number;

programming_language: TypeScript
filename: download-url.ts
change_type: ModificationType.MODIFY
diff: @@ -1,13 +1,13 @@
 import * as fs from 'fs';
 import * as stream from 'stream';
 import * as util from 'util';
-import { URL } from 'url';
-import fetch from 'node-fetch';
-import { getAgentByUrl } from './fetch';
-import { AbortController } from 'abort-controller';
+import got, * as Got from 'got';
+import { httpAgent, httpsAgent } from './fetch';
 import config from '@/config/index';
 import * as chalk from 'chalk';
 import Logger from '@/services/logger';
+import * as IPCIDR from 'ip-cidr';
+const PrivateIp = require('private-ip');
 
 const pipeline = util.promisify(stream.pipeline);
 
@@ -15,26 +15,57 @@ export async function downloadUrl(url: string, path: string) {
 	const logger = new Logger('download');
 
 	logger.info(`Downloading ${chalk.cyan(url)} ...`);
-	const controller = new AbortController();
-	setTimeout(() => {
-		controller.abort();
-	}, 60 * 1000);
 
-	const response = await fetch(new URL(url).href, {
+	const timeout = 30 * 1000;
+	const operationTimeout = 60 * 1000;
+
+	const req = got.stream(url, {
 		headers: {
 			'User-Agent': config.userAgent
 		},
-		timeout: 10 * 1000,
-		signal: controller.signal,
-		agent: getAgentByUrl,
+		timeout: {
+			lookup: timeout,
+			connect: timeout,
+			secureConnect: timeout,
+			socket: timeout,	// read timeout
+			response: timeout,
+			send: timeout,
+			request: operationTimeout,	// whole operation timeout
+		},
+		agent: {
+			http: httpAgent,
+			https: httpsAgent,
+		},
+		retry: 0,
+	}).on('response', (res: Got.Response) => {
+		if ((process.env.NODE_ENV === 'production' || process.env.NODE_ENV === 'test') && !config.proxy && res.ip) {
+			if (isPrivateIp(res.ip)) {
+				logger.warn(`Blocked address: ${res.ip}`);
+				req.destroy();
+			}
+		}
+	}).on('error', (e: any) => {
+		if (e.name === 'HTTPError') {
+			const statusCode = e.response?.statusCode;
+			const statusMessage = e.response?.statusMessage;
+			e.name = `StatusError`;
+			e.statusCode = statusCode;
+			e.message = `${statusCode} ${statusMessage}`;
+		}
 	});
 
-	if (!response.ok) {
-		logger.error(`Got ${response.status} (${url})`);
-		throw response.status;
-	}
-
-	await pipeline(response.body, fs.createWriteStream(path));
+	await pipeline(req, fs.createWriteStream(path));
 
 	logger.succ(`Download finished: ${chalk.cyan(url)}`);
 }
+
+function isPrivateIp(ip: string) {
+	for (const net of config.allowedPrivateNetworks || []) {
+		const cidr = new IPCIDR(net);
+		if (cidr.contains(ip)) {
+			return false;
+		}
+	}
+
+	return PrivateIp(ip);
+}

programming_language: TypeScript
filename: send-drive-file.ts
change_type: ModificationType.MODIFY
diff: @@ -83,10 +83,10 @@ export default async function(ctx: Koa.Context) {
 				ctx.set('Content-Type', image.type);
 				ctx.set('Cache-Control', 'max-age=31536000, immutable');
 			} catch (e) {
-				serverLogger.error(e);
+				serverLogger.error(e.statusCode);
 
-				if (typeof e == 'number' && e >= 400 && e < 500) {
-					ctx.status = e;
+				if (typeof e.statusCode === 'number' && e.statusCode >= 400 && e.statusCode < 500) {
+					ctx.status = e.statusCode;
 					ctx.set('Cache-Control', 'max-age=86400');
 				} else {
 					ctx.status = 500;

programming_language: TypeScript
filename: proxy-media.ts
change_type: ModificationType.MODIFY
diff: @@ -39,8 +39,8 @@ export async function proxyMedia(ctx: Koa.Context) {
 	} catch (e) {
 		serverLogger.error(e);
 
-		if (typeof e == 'number' && e >= 400 && e < 500) {
-			ctx.status = e;
+		if (typeof e.statusCode === 'number' && e.statusCode >= 400 && e.statusCode < 500) {
+			ctx.status = e.statusCode;
 		} else {
 			ctx.status = 500;
 		}

programming_language: TypeScript
filename: yarn.lock
change_type: ModificationType.MODIFY
diff: @@ -5742,6 +5742,27 @@ ioredis@^4.27.0:
     redis-parser "^3.0.0"
     standard-as-callback "^2.1.0"
 
+ip-address@^7.1.0:
+  version "7.1.0"
+  resolved "https://registry.yarnpkg.com/ip-address/-/ip-address-7.1.0.tgz#4a9c699e75b51cbeb18b38de8ed216efa1a490c5"
+  integrity sha512-V9pWC/VJf2lsXqP7IWJ+pe3P1/HCYGBMZrrnT62niLGjAfCbeiwXMUxaeHvnVlz19O27pvXP4azs+Pj/A0x+SQ==
+  dependencies:
+    jsbn "1.1.0"
+    sprintf-js "1.1.2"
+
+ip-cidr@3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/ip-cidr/-/ip-cidr-3.0.4.tgz#a915c47e00f47ea8d5f8ed662ea6161471c44375"
+  integrity sha512-pKNiqmBlTvEkhaLAa3+FOmYSY0/jjADVxxjA3NbujZZTT8mjLI90Q+6mwg6kd0fNm0RuAOkWJ1u1a/ETmlrPNQ==
+  dependencies:
+    ip-address "^7.1.0"
+    jsbn "^1.1.0"
+
+ip-regex@^4.3.0:
+  version "4.3.0"
+  resolved "https://registry.yarnpkg.com/ip-regex/-/ip-regex-4.3.0.tgz#687275ab0f57fa76978ff8f4dddc8a23d5990db5"
+  integrity sha512-B9ZWJxHHOHUhUjCPrMpLD4xEq35bUTClHM1S6CBU5ixQnkZmwipwgc96vAd7AAGM9TGHvJR+Uss+/Ak6UphK+Q==
+
 ip@^1.1.5:
   version "1.1.5"
   resolved "https://registry.yarnpkg.com/ip/-/ip-1.1.5.tgz#bdded70114290828c0a039e72ef25f5aaec4354a"
@@ -6238,6 +6259,11 @@ js-yaml@~3.7.0:
     argparse "^1.0.7"
     esprima "^2.6.0"
 
+jsbn@1.1.0, jsbn@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/jsbn/-/jsbn-1.1.0.tgz#b01307cb29b618a1ed26ec79e911f803c4da0040"
+  integrity sha1-sBMHyym2GKHtJux56RH4A8TaAEA=
+
 jsbn@~0.1.0:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/jsbn/-/jsbn-0.1.1.tgz#a5e654c2e5a2deb5f201d96cefbca80c0ef2f513"
@@ -7440,6 +7466,11 @@ nested-property@4.0.0:
   resolved "https://registry.yarnpkg.com/nested-property/-/nested-property-4.0.0.tgz#a67b5a31991e701e03cdbaa6453bc5b1011bb88d"
   integrity sha512-yFehXNWRs4cM0+dz7QxCd06hTbWbSkV0ISsqBfkntU6TOY4Qm3Q88fRRLOddkGh2Qq6dZvnKVAahfhjcUvLnyA==
 
+netmask@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/netmask/-/netmask-2.0.2.tgz#8b01a07644065d536383835823bc52004ebac5e7"
+  integrity sha512-dBpDMdxv9Irdq66304OLfEmQ9tbNRFnFTuZiLo+bD+r332bBmMJ8GBLXklIXXgxd3+v9+KUnZaUR5PJMa75Gsg==
+
 next-line@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/next-line/-/next-line-1.1.0.tgz#fcae57853052b6a9bae8208e40dd7d3c2d304603"
@@ -8861,6 +8892,14 @@ prismjs@1.24.1:
   resolved "https://registry.yarnpkg.com/prismjs/-/prismjs-1.24.1.tgz#c4d7895c4d6500289482fa8936d9cdd192684036"
   integrity sha512-mNPsedLuk90RVJioIky8ANZEwYm5w9LcvCXrxHlwf4fNVSn8jEipMybMkWUyyF0JhnC+C4VcOVSBuHRKs1L5Ow==
 
+private-ip@2.2.1:
+  version "2.2.1"
+  resolved "https://registry.yarnpkg.com/private-ip/-/private-ip-2.2.1.tgz#4fe167d04e12eca5c67cdcbd3224e86b38c79253"
+  integrity sha512-jN1WT/br/VNW9xEcwHr6DjtOKxQ5qOIqmh7o+co2TWgq56pZJw99iO3UT1tWdfgsQiyK9FqG4ji3ykwpjFqITA==
+  dependencies:
+    ip-regex "^4.3.0"
+    netmask "^2.0.2"
+
 probe-image-size@7.2.1:
   version "7.2.1"
   resolved "https://registry.yarnpkg.com/probe-image-size/-/probe-image-size-7.2.1.tgz#df0c924e67e247bc94f8fcb0fad7f0081061fc44"
@@ -10103,6 +10142,11 @@ split@^1.0.0:
   dependencies:
     through "2"
 
+sprintf-js@1.1.2:
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.1.2.tgz#da1765262bf8c0f571749f2ad6c26300207ae673"
+  integrity sha512-VE0SOVEHCk7Qc8ulkWw3ntAzXuqf7S2lvwQaDLRnUeIEaKNQJzV6BwmLKhOqT61aGhfUMrXeaBk+oDGCzvhcug==
+
 sprintf-js@~1.0.2:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.0.3.tgz#04e6926f662895354f3dd015203633b857297e2c"

programming_language: Markdown