Exploitable pine heap overflow (Re: Remote pine Denial of Service)

2002-11-08T00:00:00
ID SECURITYVULNS:DOC:3722
Type securityvulns
Reporter Securityvulns
Modified 2002-11-08T00:00:00

Description

Dear Linus Sjöberg,

There is a classic and probably exploitable heap overflow in bldaddr.c addr_list_string().

else{
    char *charset = NULL;

    list = (char *)fs_get((size_t)est_size(adrlist));
    list[0] = '\0';
    rfc822_write_address_decode(list, adrlist,
                                verbose ? NULL : &charset, do_quote);
    if(charset)
      fs_give((void **)&charset);
}

est_size should calculate size of target string :

est_size(a) ADDRESS *a; { int cnt = 0;

for(; a; a = a->next){

    /* two times personal for possible quoting */
    cnt   += 2 * (a->personal  ? strlen(a->personal)  : 0);
    cnt   += (a->mailbox  ? strlen(a->mailbox)  : 0);
    cnt   += (a->adl      ? strlen(a->adl)      : 0);
    cnt   += (a->host     ? strlen(a->host)     : 0);

    /*
     * add room for:
     *   possible single space between fullname and addr
     *   left and right brackets
     *   @ sign
     *   possible : for route addr
     *   , <space>
     *
     * So I really think that adding 7 is enough.  Instead, I'll add 10.
     */
    cnt   += 10;
}

return(max(cnt, 50));  /* just making sure */

}

As you can see there is no memory resseravation for characters to be commented in mailbox.

rfc822_write_address_decode finally calls to rfc822_cat which decodes mailbox to address quoting special characters. Special characters are:

()<>@,;:\\\"[]\1\2\3\4\5\6\7\10\11\12\13\14\15\16\17\20\21\22\23\24\25\26\27\30\31\32\33\34\35\36\37\177

and, of cause, it's impossible to use \0 in shellcode.

--Thursday, November 7, 2002, 4:16:13 PM, you wrote to bugtraq@securityfocus.com:

LS> Security Advisory

LS> 23rd October 2002

LS> Remote pine version 4.44 denial of service

LS> Name: Pine version 4.44 LS> Arch: Redhat 7.2 i386 LS> Severity: Medium LS> Vendor URL: http://www.washington.edu/pine/ LS> Author: Linus Sj&#246;berg (lsjoberg@aland.net) LS> Vendor notified: 14:th October 2002 LS> Vendor response: 14:th October 2002 LS> Vendor fix: ??????

LS> Impact: An attacker can send a fully legal email message with a crafted LS> From-header and thus forcing pine to core dump on startup. LS> The only way to launch pine is manually removing the bad message LS> either directly from the spool, or from another MUA. Until the LS> message has been removed or edited there is no way of accessing LS> the INBOX using pine.

LS> Description LS> *****

LS> When pine detects an email with a From-header looking like LS> From: LS> "\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\"\""@host.fubar LS> it will die with a segmentation fault. Note that the address is fully LS> legal, even if quite unusable.

LS> When i reproduced the problem with a pine running within gdb I got the LS> following backtrack: LS> #0 0x401ea490 in chunk_free (ar_ptr=0x4029e300, p=0x83b65d8) at LS> malloc.c:3231 LS> #1 0x401ea3f4 in libc_free (mem=0x83b65e0) at malloc.c:3154 LS> #2 0x081ef8e2 in fs_give (block=0xbfffb9b8) at fs_unix.c:60 LS> #3 0x080feb4f in set_index_addr LS> (idata=0xbfffc8c0, field=0x83012d8 "From", LS> addr=0x83b6160, prefix=0x0, width=18, LS> s=0xbfffbd11 LS> "\"\\\"\\\"\\\"\\\"\\\"\\\"\\\"\\\"\\\b`&#180;:\bX&#189;^?&#191;&#239;&#248;\036\b") LS> at mailindx.c:4508 LS> #4 0x080fb397 in format_index_line (idata=0xbfffc8c0) at mailindx.c:3376 LS> #5 0x080f9ec4 in build_header_line (state=0x839f260, stream=0x83aba88, LS> msgmap=0x83a17b0, msgno=40) at mailindx.c:2761 LS> #6 0x080f71e3 in update_index (state=0x839f260, screen=0xbfffcb90) LS> at mailindx.c:1264 LS> #7 0x080f576c in index_lister (state=0x839f260, cntxt=0x83a8d28, LS> folder=0x839f325 "INBOX", stream=0x83aba88, msgmap=0x83a17b0) LS> at mailindx.c:603 LS> #8 0x080f5347 in mail_index_screen (state=0x839f260) at mailindx.c:452 LS> #9 0x081588e6 in main (argc=1, argv=0xbfffddc4) at pine.c:1122 LS> #10 0x40185657 in libc_start_main (main=0x8156974 <main>, argc=1, LS> ubp_av=0xbfffddc4, init=0x804ab28 <_init>, fini=0x8225c70 <_fini>, LS> rtld_fini=0x4000dcd4 <_dl_fini>, stack_end=0xbfffddbc) LS> at ../sysdeps/generic/libc-start.c:129

LS> Since pine dumped core it might be possible to execute code on the victims LS> machine, but since I am not into those kind of games I leave that part for LS> others to find out.

LS> The possibility of locking somebody out from his email is important enough LS> for an advisory+update IMHO.

LS> Fix Information LS> ***

LS> Washington University replied to my posting within a few hours and LS> reported that the issue was to be fixed in version 4.50. They have not yet LS> made such a version publicly available after 1&#189; month, so I have chosen to LS> go public with this advisory even if there is no patch yet available.

-- ~/ZARAZA &#202;&#235;&#255;&#237;&#243;&#241;&#252; &#235;&#251;&#241;&#232;&#237;&#238;&#233; &#239;&#240;&#238;&#240;&#238;&#234;&#224; &#204;&#238;&#232;&#241;&#229;&#255; - &#255; &#242;&#229;&#225;&#255; &#241;&#229;&#233;&#247;&#224;&#241; &#241;&#250;&#229;&#236;. (&#210;&#226;&#229;&#237;)