Attacker Value
Moderate
(2 users assessed)
Exploitability
Moderate
(2 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2020-9484 — PersistentManager Java deserialization vulnerability

Disclosure Date: May 20, 2020
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

When using Apache Tomcat versions 10.0.0-M1 to 10.0.0-M4, 9.0.0.M1 to 9.0.34, 8.5.0 to 8.5.54 and 7.0.0 to 7.0.103 if a) an attacker is able to control the contents and name of a file on the server; and b) the server is configured to use the PersistenceManager with a FileStore; and c) the PersistenceManager is configured with sessionAttributeValueClassNameFilter=“null” (the default unless a SecurityManager is used) or a sufficiently lax filter to allow the attacker provided object to be deserialized; and d) the attacker knows the relative file path from the storage location used by FileStore to the file the attacker has control over; then, using a specifically crafted request, the attacker will be able to trigger remote code execution via deserialization of the file under their control. Note that all of conditions a) to d) must be true for the attack to succeed.

Add Assessment

6
Ratings
Technical Analysis

This attack can have high impact (RCE), but the conditions that need to be met make the likelihood of exploitation low.

  1. PersistentManager needs to be enabled manually by the tomcat administrator. This is likely to happen only on websites with high traffic loads (but not too high, as it will be more likely that a JDBC Store is used instead of a File Store)
  2. The attacker has to find a separate file upload vulnerability to place the malicious serialized file on the server.
  3. There have to be libraries on the classpath which are vulnerable to be exploited by a Java deserialization attack (e.g. gadgets).

However, a large range of versions of tomcat are affected.

More info in this article: https://www.redtimmy.com/java-hacking/apache-tomcat-rce-by-deserialization-cve-2020-9484-write-up-and-exploit/

2
Ratings
Technical Analysis

@cblack-r7 and I looked at this a couple weeks ago, specifically https://seclists.org/oss-sec/2020/q2/136 and https://github.com/IdealDreamLast/CVE-2020-9484. I did a double take because I thought it included a file write. Not so. There are a handful of prerequisites that mitigate the impact of this vulnerability.

If the stars align, this could be valuable, since Tomcat is everywhere. But I don’t think it’s worth writing an exploit for this, beyond a PoC, since exploitation is so niche. @redtimmy’s writeup is most excellent. Go read that.

CVSS V3 Severity and Metrics
Base Score:
7.0 High
Impact Score:
5.9
Exploitability Score:
1
Vector:
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
High
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Vendors

  • apache,
  • canonical,
  • debian,
  • fedoraproject,
  • mcafee,
  • opensuse,
  • oracle

Products

  • agile engineering data management 6.2.1.0,
  • agile plm 9.3.3,
  • agile plm 9.3.5,
  • agile plm 9.3.6,
  • communications cloud native core binding support function 1.10.0,
  • communications cloud native core policy 1.14.0,
  • communications diameter signaling router,
  • communications element manager,
  • communications instant messaging server 10.0.1.4.0,
  • communications session report manager,
  • communications session route manager,
  • database 12.2.0.1,
  • database 19c,
  • database 21c,
  • debian linux 10.0,
  • debian linux 8.0,
  • debian linux 9.0,
  • epolicy orchestrator 5.10.0,
  • epolicy orchestrator 5.9.0,
  • epolicy orchestrator 5.9.1,
  • fedora 31,
  • fedora 32,
  • fmw platform 12.2.1.3.0,
  • fmw platform 12.2.1.4.0,
  • hospitality guest access 4.2.0,
  • hospitality guest access 4.2.1,
  • instantis enterprisetrack,
  • leap 15.1,
  • managed file transfer 12.2.1.3.0,
  • managed file transfer 12.2.1.4.0,
  • mysql enterprise monitor,
  • retail order broker 15.0,
  • siebel apps - marketing,
  • siebel ui framework,
  • tomcat,
  • tomcat 10.0.0,
  • tomcat 9.0.0,
  • transportation management 6.3.7,
  • ubuntu linux 16.04,
  • ubuntu linux 20.04,
  • workload manager 12.2.0.1,
  • workload manager 18c,
  • workload manager 19c

References

Advisory
Exploit
PoCs that have not been added by contributors directly have been sourced from: nomi-sec/PoC-in-GitHub.
A PoC added here by the AKB Worker must have at least 2 GitHub stars.

Additional Info

Technical Analysis