iDEFENSE Security Advisory 02.17.04 Ipswitch IMail LDAP Daemon Remote Buffer Overflow http://www.idefense.com/application/poi/display?id=74 February 17, 2004 I. BACKGROUND Ipswitch IMail server is a Windows based messaging solution with a customer base of over 53 million users. More information about the application is available at http://www.ipswitch.com/products/IMail_Server/index.html. II. DESCRIPTION Exploitation of a remote buffer overflow within the LDAP daemon of Ipswitch IMAIL Server allows attackers to execute arbitrary code under administrator privileges. LDAP messages are comprised of various tags consisting of an identifier, a length and the content. An integer is represented in LDAP by the identifier byte 0x02, followed by the length of the integer in bytes. This is followed by the actual integer itself. As an example the following tag: 0x02 0x03 0x0A 0x25 0xBD represents the integer 665,501 (0xA25BD). The problem exists due to insufficient bounds checking upon copying of user supplied data with large tag lengths to a stack based buffer. The following assembly instruction can be abused to overwrite memory addresses as offsets from the current frame pointer because the attacker has control over ecx and var_4 at the time of exploitation: .text:00401188 mov byte ptr [ebp+ecx+var_4], dl An attacker can utilize this to overwrite the address of the Global Exception Handler, which can be found at a static distance from the frame pointer. Overwriting this address with that of a memory location containing a JMP/CALL ebx instruction (in Windows 2000) or a POP xxx POP xxx RET instruction (in Windows XP), allows the attacker to redirect the flow of control to his or her own supplied code. III. ANALYSIS Successful exploitation allows unauthenticated remote attackers to execute arbitrary code under administrator privileges. Exploitation is possible across both Windows 2000 and XP platforms. However, it requires minor changes in order to work. IV. DETECTION iDEFENSE has confirmed that the LDAP daemon (iLDAP.exe ver. 3.9.15.10) shipping with IMail Server version 8.03 is vulnerable. It us suspected that earlier versions are vulnerable as well. V. WORKAROUNDS Disable or firewall the LDAP service (TCP port 389) if unneeded. VI. RECOVERY Successful exploitation can cause the LDAP daemon to crash and will require a restart in order to resume normal operation. VII. VENDOR RESPONSE "Testing has completed their review of 8.05 Hotfix 2 and we are ready to release." The fix will be available for download at: http://www.ipswitch.com/support/imail/releases/imail_professional/im805H F2.html VIII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet. IX. DISCLOSURE TIMELINE October 31, 2003 Exploit acquired by iDEFENSE February 2, 2004 Initial vendor notification February 3, 2004 iDEFENSE clients notified February 3, 2004 Vendor response received February 17, 2004 Coordinated public disclosure
