CVS 'History' Command Discloses to Remote Authenticated Users Whether Files Exist or Not
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SecurityTracker Alert ID: 1010958
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SecurityTracker URL: http://securitytracker.com/id?1010958
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CVE Reference: CAN-2004-0778
(Links to External Site)
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Date: Aug 16 2004
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Impact: Disclosure of system information, Disclosure of user information
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Fix Available: Yes
Vendor Confirmed: Yes
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Advisory: iDEFENSE
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Version(s): prior to 1.11.17 and 1.12.9
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Description: iDEFENSE reported an information disclosure vulnerability in CVS. A remote authenticated user can determine if certain specified files and directories exist.
It is reported that there is an undocumented switch in the 'history' command in 'src/history.c'. A remote authenticated user can
supply an arbitrary filename to the '-X' command switch (used to specify the history file) and then analyze the resulting error
messages to determine if the named file exists on the target system and if the CVS process has access to the file.
The vendor
was reportedly notified on July 22, 2004. [Editor's note: This notification date is after the date of the vendor fix (June 9,
2004).
The original advisory is available at:
http://www.idefense.com/application/poi/display?id=130&type=vulnerabilities
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Impact: A remote authenticated user can determine if files or directories exist on the target system. The user can also determine if the CVS daemon has access to the files or directories.
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Solution: The vendor issued fixed versions (1.11.17 and 1.12.9), available at:
https://ccvs.cvshome.org/servlets/ProjectDownloadList
[Editor's
note: These fixed versions were released on or about June 9, 2004 to correct some other vulnerabilities, as previously reported
in Alert ID 1010438.]
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Vendor URL: www.cvshome.org/ (Links to External Site)
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Cause: Access control error, State error
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Underlying OS: Linux (Any), UNIX (Any)
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Reported By: idlabs-advisories@idefense.com
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Mon, 16 Aug 2004 11:53:02 -0400
From: idlabs-advisories@idefense.com
Subject: iDEFENSE Security Advisory 08.16.04: CVS Undocumented Flag
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CVS Undocumented Flag Information Disclosure Vulnerability
iDEFENSE Security Advisory 08.16.04
www.idefense.com/application/poi/display?id=130&type=vulnerabilities
August 16, 2004
I. BACKGROUND
CVS (Concurrent Versions System) is an open-source network-transparent
version control system.
II. DESCRIPTION
Remote exploitation of an information disclosure vulnerability in
Concurrent Versions Systems (CVS) allows attackers to glean information.
The vulnerability exists within an undocumented switch to the 'history'
command implemented in src/history.c. The -X command specifies the name
of the history file allowing an attacker to determine whether arbitrary
system files and directories exist and whether or not the CVS process
has access to them. The following output from iDEFENSE's proof of
concept code demonstrates the impact of this vulnerability:
The file /etc/shells exists and is readable by the CVS daemon:
$ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /etc/shells
Connected to server.
E cvs server: warning: history line 1 invalid
E cvs server: warning: history line 2 invalid
...
E cvs server: warning: history line 7 invalid
M No records selected.
ok
The file /usr/bin/password exists and is not readable by the CVS daemon:
$ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /usr/bin/passwd
Connected to server.
E cvs [server aborted]: cannot open history file: /usr/bin/passwd:
Permission denied
error
The file /etc/foo does not exist.
$ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /etc/foo \
Connected to server.
E cvs [server aborted]: cannot open history file: /etc/foo: No \
such file or directory
error
/tmp is a directory.
$ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /tmp
Connected to server.
E cvs [server aborted]: error reading history file: Is a directory
error
III. ANALYSIS
Successful exploitation allows remote attackers with credentials to the
affected CVS server to determine whether or not arbitrary system files
and directories exist and are accessible under the permissions of the
user that the CVS daemon runs under.
IV. DETECTION
iDEFENSE has confirmed the existence of this vulnerability in CVS
version 1.11. Earlier versions are suspected as being vulnerable as
well.
V. VENDOR RESPONSE
This issue was patched in the latest (June 9th) releases of CVS,
specifically 1.11.17 & 1.12.9.
VI. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0778 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.
VII. DISCLOSURE TIMELINE
07/22/2004 Initial vendor notification
07/22/2004 iDEFENSE clients notified
08/05/2004 Initial vendor response
08/16/2004 Public Disclosure
VIII. CREDIT
An anonymous contributor is credited with discovering this
vulnerability.
Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp
VI. LEGAL NOTICES
Copyright (c) 2004 iDEFENSE, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.
Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.
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