Tuesday, August 30, 2005

[UNIX] GNU rm Denial of Service

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GNU rm Denial of Service
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SUMMARY

" <http://www.gnu.org/software/fileutils/fileutils.html> The GNU File
Utilities are the basic file-manipulation utilities of the GNU operating
system."

When attempting to delete big list of directories in directory-tree, rm
crashes.

DETAILS

Vulnerable Systems:
* rm (fileutils) version 4.1

Immune Systems:
* rm (fileutils) version 5.2.1

Deleting 14986 (or more) sub directories with the same directory-tree with
rm allow users to crash rm and may even execute arbitrary code.

Proof of Concept:
$ gdb -q /bin/rm
(no debugging symbols found)...(gdb)
(gdb) r -rf A
Starting program: /bin/rm -rf A
(no debugging symbols found)...(no debugging symbols found)...
Program received signal SIGSEGV, Segmentation fault.
0xb7e880dc in __lxstat64 () from /lib/libc.so.6
(gdb) i r
eax 0xbf711138 -1083109064
ecx 0x804d820 134535200
edx 0x0 0
ebx 0x0 0
esp 0xbf711000 0xbf711000
ebp 0xbf711088 0xbf711088
esi 0x809c1fb 134857211
edi 0x80a6c70 134900848
eip 0xb7e880dc 0xb7e880dc
eflags 0x10286 66182
cs 0x73 115
ss 0x7b 123
ds 0x7b 123
es 0x7b 123
fs 0x0 0
gs 0x0 0
fctrl 0x37f 895
fstat 0x20 32
ftag 0xffff 65535
fiseg 0x73 115
fioff 0x804b728 134526760
foseg 0x7b 123
fooff 0x804d828 134535208
fop 0x6d9 1753
mxcsr 0x1f80 8064
orig_eax 0xffffffff -1
(gdb)

ADDITIONAL INFORMATION

The information has been provided by <mailto:h4sh@globo.com> Carlos
Carvalho.
The original article can be found at:
<http://nutshell.gotfault.net/papers/adv_rm.txt>
http://nutshell.gotfault.net/papers/adv_rm.txt

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