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Errant command quoting in `org.eclipse.jetty.servlets.CGI` Servlet

Low
sbordet published GHSA-3gh6-v5v9-6v9j Sep 14, 2023

Package

maven org.eclipse.jetty.ee10:jetty-ee10-servlets (Maven)

Affected versions

<= 12.0.0-beta1

Patched versions

12.0.0-beta2
maven org.eclipse.jetty.ee8:jetty-ee8-servlets (Maven)
<= 12.0.0-beta1
12.0.0-beta2
maven org.eclipse.jetty.ee9:jetty-ee9-servlets (Maven)
<= 12.0.0-beta1
12.0.0-beta2
maven org.eclipse.jetty:jetty-servlets (Maven)
>= 9.0.0, <= 9.4.51
>= 10.0.0, <= 10.0.15
>= 11.0.0, <= 11.0.15
9.4.52
10.0.16
11.0.16

Description

If a user sends a request to a org.eclipse.jetty.servlets.CGI Servlet for a binary with a space in its name, the servlet
will escape the command by wrapping it in quotation marks. This wrapped command, plus
an optional command prefix, will then be executed through a call to Runtime.exec. If the
original binary name provided by the user contains a quotation mark followed by a space,
the resulting command line will contain multiple tokens instead of one. For example, if a
request references a binary called file” name “here, the escaping algorithm will
generate the command line string “file” name “here”, which will invoke the binary
named file, not the one that the user requested.

if (execCmd.length() > 0 && execCmd.charAt(0) != '"' && execCmd.contains(" "))
execCmd = "\"" + execCmd + "\"";

Exploit Scenario

The cgi-bin directory contains a binary named exec and a subdirectory named exec”
commands, which contains a file called bin1. The user sends to the CGI servlet a request
for the filename exec” commands/bin1. This request will pass the file existence check on
lines 194 through 205. The servlet will add quotation marks around this filename, resulting
in the command line string “exec” commands/bin1”. When this string is passed to
Runtime.exec, instead of executing the bin1 binary, the server will execute the exec
binary with the argument commands/file1”. In addition to being incorrect, this behavior
may bypass alias checks, and it may cause other unintended behaviors if a command prefix
is configured.

If the useFullPath configuration setting is off, the command need not pass the existence
check. The attack would not rely on a binary and subdirectory having similar names, and
the attack will succeed on a much wider variety of directory structures.

Impact

Users of the org.eclipse.jetty.servlets.CGI Servlet with a very specific command structure may have the wrong command executed.

Patches

No patch.
In Jetty 9.x, 10.x, and 11.x the org.eclipse.jetty.servlets.CGI has been deprecated.
In Jetty 12 (all environments) the org.eclipse.jetty.servlets.CGI has been entirely removed.

Workarounds

The org.eclipse.jetty.servlets.CGI Servlet should not be used. Fast CGI support is available instead.

References

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N

CVE ID

CVE-2023-36479

Weaknesses

Credits