truecrypt_foundation truecrypt 信息泄露漏洞

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漏洞ID 1185492 漏洞类型 信息泄露
发布时间 2008-09-03 更新时间 2008-09-03
CVE编号 CVE-2008-3899 CNNVD-ID CNNVD-200809-043
漏洞平台 N/A CVSS评分 2.1
|漏洞来源
https://www.securityfocus.com/bid/84849
https://cxsecurity.com/issue/WLB-2008090081
http://www.cnnvd.org.cn/web/xxk/ldxqById.tag?CNNVD=CNNVD-200809-043
|漏洞详情
TrueCrypt是一款免费,开源的支持WindowsVista/XP/2000andLinux的绿色虚拟加密磁盘工具。TrueCrypt5.0版本在BIOS键盘缓冲区内储存pre-boot权限密码而且不会在使用后清空该缓冲区,这会允许本地用户通过读取与该缓冲区有关的物理内存位置来获得敏感信息。
|漏洞EXP
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- -----------------------------------------------------------------------
[ iViZ Security Advisory 08-003                            25/08/2008 ]
- -----------------------------------------------------------------------
iViZ Techno Solutions Pvt. Ltd.
                                            http://www.ivizsecurity.com
- -----------------------------------------------------------------------

* Title:     TrueCrypt Security Model bypass exploiting wrong BIOS API
             usage
* Date:      25/08/2008
* Software:  TrueCrypt

- --[ Synopsis:

The password checking routine of TrueCrypt fails to sanitize the
    BIOS keyboard buffer before AND after reading passwords.

- --[ Affected Software:

* TrueCrypt 5.0 (possibly older versions also)

- --[ Technical description:

Truecrypt's pre-boot authentication routines use the BIOS API to
    read user input via the keyboard. The BIOS internally copies the
    keystrokes in a RAM structure called the BIOS Keyboard buffer
    inside the BIOS Data Area. This buffer is not flushed after use,
    resulting in potential plain text password leakage once the OS
    is fully booted, assuming the attacker can read the password at
    physical memory location 0x40:0x1e. It is also possible for a root
    user to reboot the computer by instrumenting the BIOS keyboard
    buffer in spite of the full disk encryption.

- --[ Impact:

1) Plain text password disclosure.
     Required privileges to perform this operation are OS dependent,
     from unprivileged users under Windows (any), to root under most
     Unix.

2) A privileged attacker able to write to the MBR and knowing the
     password (for instance thanks to 1), is able to reboot the computer
     in spite of the password prompted at boot time (and in spite of
     disk encryption) by initializing the BIOS keyboard buffer with the
     correct password (using an intermediary bootloader that will in turn
     run TrueCrypt).

- --[ Full Technical Whitepaper

http://www.ivizsecurity.com/research/preboot/preboot_whitepaper.pdf

- --[ Vendor response:

* Vendor denies the vulnerability
  * Fixed in updated versions

- --[ Credits:

This vulnerability was discovered by Security Researcher
    Jonathan Brossard from iViZ Techno Solutions Pvt. Ltd.

- --[ Disclosure timeline:

* First private disclosure to vendor on July 29th 2008
  * First vendor reply on July 29th 2008, denying the
    vulnerability.
  * First Public disclosure at Defcon 16 on August 10th 2008

- --[ Reference:

http://www.ivizsecurity.com/security-advisory.html
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|受影响的产品
Truecrypt Foundation Truecrypt 5.0
|参考资料

来源:BUGTRAQ
名称:20080825[IVIZ-08-003]TrueCryptSecurityModelbypassexploitingwrongBIOSAPIusage
链接:http://www.securityfocus.com/archive/1/archive/1/495805/100/0/threaded
来源:MISC
链接:http://www.ivizsecurity.com/research/preboot/preboot_whitepaper.pdf
来源:MISC
链接:http://www.ivizsecurity.com/preboot-patch.html
来源:SREASON
名称:4203
链接:http://securityreason.com/securityalert/4203