发布日期：2005-10-31
更新日期：2005-11-14

受影响系统：

Jed Wing CHM lib 0.35
Jed Wing CHM lib 0.33
Jed Wing CHM lib 0.32
Jed Wing CHM lib 0.31
Jed Wing CHM lib 0.3
Jed Wing CHM lib 0.2
Jed Wing CHM lib 0.1

不受影响系统：

Jed Wing CHM lib 0.36

描述：

---

BUGTRAQ  ID: 15234
CVE(CAN) ID: CVE-2005-2930

chmlib是用于处理Microsoft ITSS/CHM格式文件的函数库。

各种Linux版本捆绑的chmlib存在栈溢出漏洞，远程攻击者可能利用此漏洞在主机上执行任意指令。

在chm_lib.c的以下代码中，处理CHM文件时存在未检查的内存拷贝：

static UChar *_chm_find_in_PMGL(UChar *page_buf,
                                UInt32
block_len,
                                const
char *objPath)
{
[...]
  char buffer[CHM_MAX_PATHLEN+1];    
    /* figure out where to start and end */
    cur = page_buf;
    hremain = _CHM_PMGL_LEN;
    if (! _unmarshal_pmgl_header(&cur, &hremain, &header))
        return NULL;
    end = page_buf + block_len - (header.free_space);
    
    /* now, scan progressively */
    while (cur < end)
    {
        /* grab the name */
        temp = cur;
        strLen = _chm_parse_cword(&cur);
        if (! _chm_parse_UTF8(&cur, strLen, buffer))
            return NULL;
[..]

可以强制_chm_parse_cword返回大于CHM_MAX_PATHLEN的值。然后可以在拷贝用户控制数据时将该值拷贝到CHM_MAX_PATHLEN大小的栈缓冲区，这可能允许攻击者通过覆盖栈中保存的返回地址控制执行流，从而执行任意代码。

<*来源：iDEFENSE
  
  链接：http://www.idefense.com/application/poi/display?id=332&type=vulnerabilities
        http://www.debian.org/security/2005/dsa-886
*>

建议：

---

临时解决方法：

* 不要打开不可信任来源的CHM文件。

厂商补丁：

Debian
------
Debian已经为此发布了一个安全公告（DSA-886-1）以及相应补丁:
DSA-886-1：New chmlib packages fix several vulnerabilities
链接：http://www.debian.org/security/2005/dsa-886

补丁下载：
Source archives:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1.dsc
Size/MD5 checksum:      604 022d55ea43ef4a54648b0823163c4a07
http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1.diff.gz
Size/MD5 checksum:    15698 55eeab9a32a66c5e123ab51f3d7427df
http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35.orig.tar.gz
Size/MD5 checksum:   368428 8fa0e692b2606a03fb51589f66a82eec

Alpha architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_alpha.deb
Size/MD5 checksum:    25688 2471920dc5214b95a44e50e2a8800ada
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_alpha.deb
Size/MD5 checksum:    18576 0b1d802a79cea68c00d36cd9cb7a36cd
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_alpha.deb
Size/MD5 checksum:    25544 23306cc3f7b0772f744707c86fa9258a

AMD64 architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_amd64.deb
Size/MD5 checksum:    23748 e5a72c3311e7b00d6295a75f7bb37560
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_amd64.deb
Size/MD5 checksum:    16928 8a2d68579e364a284c03dcc4b9a01e37
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_amd64.deb
Size/MD5 checksum:    22564 50d2a8d694d1bf7251d18b4f7b02ede7

ARM architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_arm.deb
Size/MD5 checksum:    25242 ec14b38be010c3f1fee93dd618124c5e
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_arm.deb
Size/MD5 checksum:    15962 5e1ec37635078cc29b9f2a4f91f9b20e
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_arm.deb
Size/MD5 checksum:    24000 bc84ed2d77918f6eb4378f35f43cd4e5

Intel IA-32 architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_i386.deb
Size/MD5 checksum:    24872 fbea0ba2924295a9f553c346eeb164af
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_i386.deb
Size/MD5 checksum:    16094 de94d72e5414d1b218fd32f11cd7351b
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_i386.deb
Size/MD5 checksum:    22872 3e37bda96c284423f467aecb88e8dc98

Intel IA-64 architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_ia64.deb
Size/MD5 checksum:    28504 ef19dde34158fa817781c685d2499cbb
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_ia64.deb
Size/MD5 checksum:    19348 e15dc8288ba0a0bee7a9490c4fe653de
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_ia64.deb
Size/MD5 checksum:    27268 497388fcd7e08a7558dde96082b2707a

HP Precision architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_hppa.deb
Size/MD5 checksum:    27748 1be03e42641d4a3a409bf5604e1b15a8
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_hppa.deb
Size/MD5 checksum:    18060 290679f0522440bd4ab925fb3f883b60
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_hppa.deb
Size/MD5 checksum:    24192 7e4c8b5b62bb7ab2eb14f01e54b64453

Motorola 680x0 architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_m68k.deb
Size/MD5 checksum:    23124 e845c33b36a51d713fd4cf5ba24aa136
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_m68k.deb
Size/MD5 checksum:    16256 25a7901e4b91497528bdf582b43b5df3
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_m68k.deb
Size/MD5 checksum:    21626 aa4166c4ee0660cbf5ecefff086e871b

Big endian MIPS architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_mips.deb
Size/MD5 checksum:    26552 456bd641bda1da859c9769c5dbac0212
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_mips.deb
Size/MD5 checksum:    23108 5f289432c7bcfb2bf5945b688aa3e80a
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_mips.deb
Size/MD5 checksum:    25098 589bb8b01be1943c4813afb477b1a83c

Little endian MIPS architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_mipsel.deb
Size/MD5 checksum:    26582 36348c9aa4b47d9426481a2faf90e98a
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_mipsel.deb
Size/MD5 checksum:    23128 c970a6faf21ba157d72c1dd8720fe307
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_mipsel.deb
Size/MD5 checksum:    25082 4bb261ab9c4b19623a0e53e0063f920f

PowerPC architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_powerpc.deb
Size/MD5 checksum:    27380 7e7d08b907286bf4b326a97ed0b9ad72
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_powerpc.deb
Size/MD5 checksum:    22032 a24a33a3eba0b35608f23159fab58a4d
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_powerpc.deb
Size/MD5 checksum:    23558 6a0564ea6c10034569bf0b428c372dd9

IBM S/390 architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_s390.deb
Size/MD5 checksum:    26606 d2b7c824f1118f3088daacd66c9e6e61
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_s390.deb
Size/MD5 checksum:    17486 42591c148ddfb9df1a3c1d9006e609e5
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_s390.deb
Size/MD5 checksum:    23454 e4a6426fe3831ebb9e2afc47565fa191

Sun Sparc architecture:

http://security.debian.org/pool/updates/main/c/chmlib/chmlib_0.35-6sarge1_sparc.deb
Size/MD5 checksum:    24332 b41c04b1d6df50931ddfe8eafa61d19f
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-bin_0.35-6sarge1_sparc.deb
Size/MD5 checksum:    16110 17aba1dae25700043a23aa9863a190f0
http://security.debian.org/pool/updates/main/c/chmlib/chmlib-dev_0.35-6sarge1_sparc.deb
Size/MD5 checksum:    22330 5e0e711c063af5b5c982224d1eeef5e5

补丁安装方法：

1. 手工安装补丁包：

  首先，使用下面的命令来下载补丁软件：
  # wget url  (url是补丁下载链接地址)

  然后，使用下面的命令来安装补丁：  
  # dpkg -i file.deb (file是相应的补丁名)

2. 使用apt-get自动安装补丁包：

   首先，使用下面的命令更新内部数据库：
   # apt-get update
  
   然后，使用下面的命令安装更新软件包：
   # apt-get upgrade

Jed Wing
--------
目前厂商已经发布了升级补丁以修复这个安全问题，请到厂商的主页下载：

* Jed Wing Upgrade chmlib-0.36.tgz
http://morte.jedrea.com/~jedwin/projects/chmlib/chmlib-0.36.tgz

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