CyberSecBulletin
CVE-2017-9841Exploited in the wildNVD status: Analyzed

PHPUnit Command Injection

Published Updated By the CyberSecBulletin desk

CVE-2017-9841 is a critical-severity improper control of generation of code vulnerability in Phpunit from Phpunit Project, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 5.6.3 as the first without the flaw, so updating Phpunit to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on February 15, 2022, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Phpunit to 5.6.3 or a later version.
  2. CISA's required action: Apply updates per vendor instructions.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Phpunit ProjectPhpunit4.8.27 and earlier; 5.0.0 up to, but not including, 5.6.35.6.3
OracleCommunications Diameter Signaling Router8.0.0 through 8.5.0Not stated

Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalNVD
CVSS 3.19.8CriticalCISA (ADP)
CVSS 2.07.5HighNVD

Official description

Util/PHP/eval-stdin.php in PHPUnit before 4.8.28 and 5.x before 5.6.3 allows remote attackers to execute arbitrary PHP code via HTTP POST data beginning with a "<?php " substring, as demonstrated by an attack on a site with an exposed /vendor folder, i.e., external access to the /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php URI.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Control of Generation of Code

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

How developers prevent this class of flaw

  • Refactor your program so that you do not have to dynamically generate code.
  • Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

More Improper Control of Generation of Code vulnerabilities (CWE-94)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Recent Improper Control of Generation of Code vulnerabilities

Spotted an error? Tell us.